Refrigeration cycle device

Abstract

A refrigeration cycle device (1) comprises: a refrigerant circuit (7) through which a refrigerant circulates; a water circuit (6) having a water refrigerant heat exchanger (14) that performs heat exchange between the refrigerant and water, and a hot water supply tank (11); a pump (12) that circulates water through the water circuit (6) such that low-temperature water is supplied from an outlet (21) of the hot water supply tank (11) to the water refrigerant heat exchanger (14), and that high-temperature water obtained by heating the low-temperature water at the water refrigerant heat exchanger (14) is supplied from the water refrigerant heat exchanger (14) to the hot water supply tank (11); an indoor unit (3) that performs cooling operations; and a hot water outlet temperature sensor (37) that measures the temperature of high-temperature water as a hot water outlet temperature. When the indoor unit (3) circulates water through the water circuit (6) while performing the cooling operations, either a first cooling hot water supply mode in which the pump (12) is controlled so that the hot water outlet temperature approaches a first target hot water outlet temperature, or a second cooling hot water supply mode in which the pump (12) is controlled so that the hot water outlet temperature approaches a second target hot water outlet temperature lower than the first target hot water outlet temperature, is executed.

Description

Refrigeration cycle apparatus

[0001] The technology of the present disclosure relates to a refrigeration cycle apparatus.

[0002] A refrigeration cycle apparatus that supplies hot water heated by using waste heat during cooling operation is known (Japanese Patent No. 5865482). Such a refrigeration cycle apparatus can reduce power consumption compared to a refrigeration cycle apparatus that performs cooling and hot water supply separately.

[0003] Japanese Patent No. 5865482

[0004] In such a refrigeration cycle apparatus, while performing cooling operation, the pressure of the discharged refrigerant discharged from the compressor is increased so that the pressure saturation temperature of the discharged refrigerant is higher than the target outlet hot water temperature. Therefore, in such a refrigeration cycle apparatus, when the rotation speed of the compressor is low, a large torque is required, and there is a possibility that the reliability of the compressor cannot be ensured due to an increase in load on the shaft and bearings. Furthermore, in such a refrigeration cycle apparatus, when the rotation speed of the compressor is high, the compression ratio increases, which increases the load on the sliding portion of the compressor, and there is a possibility that the reliability of the compressor cannot be ensured.

[0005] The disclosed technology has been made in view of the above point, and an object of the disclosed technology is to improve the reliability of a compressor while reducing power consumption in a refrigeration cycle apparatus that supplies hot water heated by using waste heat during cooling operation.

[0006] A refrigeration cycle device according to one aspect of the present disclosure includes a water circuit having a refrigerant circuit through which a refrigerant circulates, a water-refrigerant heat exchanger for exchanging heat between the refrigerant and water, and a hot water supply tank; a pump for circulating water in the water circuit such that low-temperature water is supplied from the outlet of the hot water supply tank to the water-refrigerant heat exchanger, and high-temperature water, which is heated in the water-refrigerant heat exchanger, is supplied from the water-refrigerant heat exchanger to the hot water supply tank; an indoor unit for performing cooling operation; a hot water outlet temperature sensor for measuring the temperature of the high-temperature water as the hot water outlet temperature; and a control device that executes one of the following modes: a first cooling hot water supply mode for controlling the pump so that the hot water outlet temperature approaches a first target hot water outlet temperature when the indoor unit circulates water in the water circuit while performing cooling operation; and a second cooling hot water supply mode for controlling the pump so that the hot water outlet temperature approaches a second target hot water outlet temperature which is lower than the first target hot water outlet temperature.

[0007] The disclosed refrigeration cycle device can reduce power consumption and improve compressor reliability when supplying hot water heated using waste heat during cooling operation.

[0008] Figure 1 is a refrigerant circuit diagram showing the refrigeration cycle device of Example 1. Figure 2 is a block diagram of the control device.

[0009] The refrigeration cycle apparatus according to the embodiments disclosed herein will be described in detail below with reference to the drawings. However, the technology of this disclosure is not limited by the following description. Furthermore, the same reference numerals are used for identical components, and redundant explanations are omitted.

[0010] The refrigeration cycle device 1 of Embodiment 1 comprises an outdoor unit 2, an indoor unit 3, and a hot water supply unit 5, as shown in Figure 1. Figure 1 is a refrigerant circuit diagram showing the refrigeration cycle device 1 of Embodiment 1. The outdoor unit 2 is installed outside the room that is cooled by the refrigeration cycle device 1. The indoor unit 3 is installed inside the room that is cooled by the refrigeration cycle device 1. The refrigeration cycle device 1 further comprises a water circuit 6 and a refrigerant circuit 7. The water circuit 6 is located inside the hot water supply unit 5. The water circuit 6 comprises a hot water tank 11, a pump 12, a water-refrigerant heat exchanger 14, a switching valve 15, a water supply connection port 16, a pressure reducing valve 17, a hot water mixing valve 18, and a hot water connection port 19.

[0011] The hot water tank 11 stores the water that circulates in the water circuit 6. The hot water tank 11 has an outlet 21, a first inlet 22, a second inlet 23, a hot water outlet 24, and a cold water outlet 25. The outlet 21 and the cold water outlet 25 are located at the bottom of the hot water tank 11. The lower interior space of the hot water tank 11 is connected to the pump 12 via the outlet 21 and to the pressure reducing valve 17 via the cold water outlet 25. The first inlet 22 and the hot water outlet 24 are located at the top of the hot water tank 11. The upper interior space of the hot water tank 11 is connected to the switching valve 15 via the first inlet 22 and to the hot water mixing valve 18 via the hot water outlet 24. The second inlet 23 is located below the first inlet 22 and is connected to the switching valve 15.

[0012] Pump 12 is connected to the water-refrigerant heat exchanger 14. Pump 12 comprises a main body and a rotating body. The rotating body rotates relative to the main body, supplying water stored in the lower space of the hot water tank 11 to the water-refrigerant heat exchanger 14 via the outlet 21, and circulating the water through the water circuit 6. The flow rate of water supplied by pump 12 to the water-refrigerant heat exchanger 14 per unit time increases as the pump rotation speed, which indicates the number of rotations of the rotating body relative to the main body per unit time, increases. The power consumed by pump 12 also increases as the pump rotation speed increases.

[0013] The water-refrigerant heat exchanger 14 is connected to the switching valve 15. The switching valve 15 switches the flow path of the water circuit 6 so that the water-refrigerant heat exchanger 14 is connected to the first inlet 22 or to the second inlet 23.

[0014] The water supply connection port 16 is connected to the piping connected to the water supply system and is connected to the pressure reducing valve 17. The hot water mixing valve 18 is connected to the pressure reducing valve 17 and is connected to the hot water connection port 19. The hot water connection port 19 is connected to the piping connected to the faucet. An example of a faucet is a tap operated by the user.

[0015] The refrigerant circuit 7 includes a compressor 31, a refrigerant circuit switching valve 32, an outdoor heat exchanger 33, an expansion valve 34, and an indoor heat exchanger 35. The compressor 31 is located inside the outdoor unit 2. The compressor 31 includes a main body, a rotating body, an intake pipe, and a discharge pipe. The compressor 31 compresses the refrigerant drawn into the compressor 31 via the intake pipe by the rotation of the rotating body relative to the main body, and discharges the compressed refrigerant through the discharge pipe. The flow rate of refrigerant discharged by the compressor 31 per unit time increases as the compressor rotation speed, which indicates the number of rotations of the rotating body relative to the main body per unit time, increases. The power consumed by the compressor 31 increases as the compressor rotation speed increases.

[0016] The refrigerant circuit switching valve 32 is located inside the outdoor unit 2. The refrigerant circuit switching valve 32 is connected to the suction pipe and discharge pipe of the compressor 31, and to the water refrigerant heat exchanger 14, the outdoor heat exchanger 33, and the indoor heat exchanger 35. The refrigerant circuit switching valve 32 switches the refrigerant circuit 7 to one of the following cycles: the cooling-hot water cycle, the cooling cycle, and the outside air heat-absorbing-hot water cycle. When the refrigerant circuit 7 is switched to the cooling-hot water cycle, the discharge pipe of the compressor 31 is connected to the water refrigerant heat exchanger 14 and the outdoor heat exchanger 33, and the indoor heat exchanger 35 is connected to the suction pipe of the compressor 31. When the refrigerant circuit 7 is switched to the cooling cycle, the discharge pipe of the compressor 31 is connected to the outdoor heat exchanger 33, and the indoor heat exchanger 35 is connected to the suction pipe of the compressor 31. When the refrigerant circuit 7 is switched to the outside air heat intake hot water supply cycle, the discharge pipe of the compressor 31 is connected to the water refrigerant heat exchanger 14, and the outdoor heat exchanger 33 is connected to the suction pipe of the compressor 31.

[0017] The outdoor heat exchanger 33 is located inside the outdoor unit 2. The outdoor unit 2 allows outside air to pass through the outdoor heat exchanger 33. The outdoor heat exchanger 33 is connected to an expansion valve 34. The expansion valve 34 is located inside the outdoor unit 2. The expansion valve 34 is connected to a water refrigerant heat exchanger 14 and an indoor heat exchanger 35. The indoor heat exchanger 35 is located inside the indoor unit 3. The indoor unit 3 allows the air from the room in which the indoor unit 3 is installed to pass through the indoor heat exchanger 35, and blows the air that has passed through the indoor heat exchanger 35 back into the room.

[0018] The refrigeration cycle device 1 further includes an inlet water temperature sensor 36, an outlet water temperature sensor 37, and a room temperature sensor 38. The inlet water temperature sensor 36 is located inside the hot water supply unit 5. The inlet water temperature sensor 36 measures the temperature of the low-temperature water that flows out from the outlet 21 of the hot water supply tank 11 and into the water-refrigerant heat exchanger 14. The outlet water temperature sensor 37 is located inside the hot water supply unit 5. The outlet water temperature sensor 37 measures the temperature of the high-temperature water that flows out from the water-refrigerant heat exchanger 14 and into the switching valve 15. The room temperature sensor 38 is provided in the indoor unit 3. The room temperature sensor 38 measures the temperature of the room in which the indoor unit 3 is installed.

[0019] The refrigeration cycle device 1 further includes a control device 41. Figure 2 is a block diagram of the control device 41. The control device 41 is a computer and includes a storage device 42 and a CPU 43 (Central Processing Unit). The storage device 42 stores the computer program installed in the control device 41 and stores information used by the CPU 43. The CPU 43 executes the computer program installed in the control device 41. The control device 41 is connected to the pump 12, the switching valve 15, the compressor 31, and the refrigerant circuit switching valve 32, and is also connected to the inlet water temperature sensor 36, the outlet water temperature sensor 37, and the room temperature sensor 38.

[0020] The control device 41 performs multiple functions when a computer program is executed. The control device 41 includes a refrigerant circuit switching unit 44, a compressor control unit 45, a switching valve control unit 46, and a pump control unit 47 as multiple functions. The refrigerant circuit switching unit 44 controls the refrigerant circuit switching valve 32 so that the refrigerant circuit 7 switches to one of the cycles: the cooling hot water supply cycle, the cooling cycle, and the outside air heat absorption hot water supply cycle. The compressor control unit 45 controls the compressor 31 to adjust the compressor rotation speed. The switching valve control unit 46 controls the switching valve 15 so that the water-refrigerant heat exchanger 14 is connected to the first inlet 22 or the second inlet 23. The pump control unit 47 controls the pump 12 to adjust the pump rotation speed based on the hot water temperature measured by the hot water temperature sensor 37.

[0021] [Operation of Refrigeration Cycle Device 1] The water pressure of the water stored inside the hot water tank 11 decreases when the faucet connected to the hot water connection port 19 is opened. Tap water supplied from the water supply connection port 16 to the pressure reducing valve 17 flows through the pressure reducing valve 17 so that when the water pressure inside the hot water tank 11 decreases, the water pressure inside the hot water tank 11 is maintained at a constant water pressure lower than the water pressure of the tap water at the water supply connection port 16. A portion of the tap water that has flowed through the pressure reducing valve 17 flows into the lower space of the hot water tank 11 via the water inlet 25. High-temperature water is stored in the upper space of the hot water tank 11, and low-temperature water, which is at a lower temperature than the high-temperature water, is stored in the lower space of the hot water tank 11. The low-temperature water stored in the lower space of the hot water tank 11 is mixed with tap water and increases as tap water flows into the lower space of the hot water tank 11 via the water inlet 25.

[0022] A portion of the high-temperature water stored in the upper space of the hot water tank 11 is pushed aside by the increasing amount of low-temperature water stored in the lower space of the hot water tank 11, and flows into the hot water mixing valve 18 via the hot water outlet 24. The amount of high-temperature water stored in the upper space of the hot water tank 11 decreases as a portion of the high-temperature water flows into the hot water mixing valve 18. The high-temperature water that flows into the hot water mixing valve 18 is mixed with the remaining portion of the tap water that has flowed through the pressure reducing valve 17, resulting in hot water at a preset hot water temperature. The hot water flows out from the faucet connected to the hot water connection port 19 because the faucet is open.

[0023] Furthermore, when the refrigeration cycle device 1 receives both a request for cooling operation and a request for hot water supply from the user, the control device 41 executes one of the following modes: first cooling and hot water supply mode, second cooling and hot water supply mode, cooling mode, and outside air heat absorption and hot water supply mode. [First cooling and hot water supply mode] In the first cooling and hot water supply mode, the control device 41 controls the switching valve 15 to switch the flow path of the water circuit 6 so that the water refrigerant heat exchanger 14 is connected to the hot water tank 11 via the first inlet 22, and drives the pump 12. The low-temperature water stored in the lower space of the hot water tank 11 flows out of the hot water tank 11 via the outlet 21 as the pump 12 is driven, and decreases in volume. The low-temperature water that has flowed out of the hot water tank 11 flows into the water refrigerant heat exchanger 14 via the pump 12.

[0024] The water-refrigerant heat exchanger 14 exchanges heat between the high-pressure gaseous refrigerant flowing into the water-refrigerant heat exchanger 14 and the low-temperature water flowing into the water-refrigerant heat exchanger 14, thereby heating the low-temperature water. The low-temperature water is heated in the water-refrigerant heat exchanger 14 and becomes high-temperature water. The high-temperature water flows into the upper space of the hot water supply tank 11 via the first inlet 22, because the water-refrigerant heat exchanger 14 is connected to the first inlet 22 via the switching valve 15. The high-temperature water stored in the hot water supply tank 11 increases as the high-temperature water heated by the water-refrigerant heat exchanger 14 flows into the upper space of the hot water supply tank 11 and mixes with the high-temperature water heated by the water-refrigerant heat exchanger 14.

[0025] When the first cooling and hot water supply mode is in operation, the control device 41 intermittently acquires the hot water outlet temperature measured by the hot water outlet temperature sensor 37 from the hot water outlet temperature sensor 37. The control device 41 controls the pump 12 and adjusts the pump rotation speed of the pump 12 so that the hot water outlet temperature approaches the first target hot water outlet temperature. That is, the control device 41 decreases the pump rotation speed when the hot water outlet temperature is lower than the first target hot water outlet temperature, and increases the pump rotation speed when the hot water outlet temperature is higher than the first target hot water outlet temperature. The first target hot water outlet temperature is, for example, the hot water outlet temperature required to store the amount of heat necessary to meet the daily hot water supply demand in the hot water supply tank 11, and 65°C is an example.

[0026] In the first cooling and hot water supply mode, the control device 41 further controls the compressor 31 and the refrigerant circuit switching valve 32 so that the indoor unit 3 performs cooling operation. Specifically, the control device 41 controls the refrigerant circuit switching valve 32 to switch the refrigerant circuit 7 to the cooling and hot water supply cycle and drive the compressor 31. The compressor 31 compresses the low-pressure gaseous refrigerant that is drawn into the compressor 31. The low-pressure gaseous refrigerant is compressed by the compressor 31 and becomes high-pressure gaseous refrigerant. Because the refrigerant circuit 7 has been switched to the cooling and hot water supply cycle, a portion of the high-pressure gaseous refrigerant flows into the water refrigerant heat exchanger 14, and the remainder of the high-pressure gaseous refrigerant flows into the outdoor heat exchanger 33.

[0027] The outdoor unit 2 allows outside air to pass through the outdoor heat exchanger 33. The outdoor heat exchanger 33 exchanges heat between the high-pressure gaseous refrigerant flowing into the outdoor heat exchanger 33 and the outside air, cooling the high-pressure gaseous refrigerant flowing into the outdoor heat exchanger 33. The high-pressure gaseous refrigerant flowing into the outdoor heat exchanger 33 is cooled and condensed by the outdoor heat exchanger 33, becoming a high-pressure liquid refrigerant. In other words, the outdoor heat exchanger 33 functions as a condenser when the first cooling and hot water supply mode is executed.

[0028] The water refrigerant heat exchanger 14 exchanges heat between the high-pressure gaseous refrigerant flowing into the water refrigerant heat exchanger 14 and the low-temperature water flowing into the water refrigerant heat exchanger 14, thereby cooling the high-pressure gaseous refrigerant flowing into the water refrigerant heat exchanger 14. The high-pressure gaseous refrigerant flowing into the water refrigerant heat exchanger 14 is cooled and condensed by the water refrigerant heat exchanger 14, becoming a high-pressure liquid refrigerant. In other words, the water refrigerant heat exchanger 14 functions as a condenser when the first cooling and hot water supply mode is executed.

[0029] The high-pressure liquid-phase refrigerant flowing out from the outdoor heat exchanger 33 and the high-pressure liquid-phase refrigerant flowing out from the water refrigerant heat exchanger 14 flow into the expansion valve 34. The expansion valve 34 reduces the pressure of the high-pressure liquid-phase refrigerant that has flowed into the expansion valve 34 from the outdoor heat exchanger 33 and the water refrigerant heat exchanger 14. The expansion valve 34 may consist of an expansion valve corresponding to the outdoor heat exchanger 33 and an expansion valve corresponding to the water refrigerant heat exchanger 14. The high-pressure liquid-phase refrigerant is reduced in pressure by the expansion valve 34 and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant flows from the expansion valve 34 into the indoor heat exchanger 35.

[0030] The indoor unit 3 passes the air from the room in which it is installed through the indoor heat exchanger 35. The indoor heat exchanger 35 exchanges heat between the air and the low-pressure gas-liquid two-phase refrigerant, cooling the air and heating the low-pressure gas-liquid two-phase refrigerant. The indoor unit 3 then blows the air cooled by the indoor heat exchanger 35 into the room. The room in which the indoor unit 3 is installed is cooled by the air cooled by the indoor heat exchanger 35 being blown into the room. The low-pressure gas-liquid two-phase refrigerant is heated by the indoor heat exchanger 35, evaporates, and becomes a low-pressure gaseous refrigerant. In other words, the indoor heat exchanger 35 functions as an evaporator when the first cooling and hot water supply mode is executed. The low-pressure gaseous refrigerant is drawn into the compressor 31 when the refrigerant circuit 7 is switched to the cooling and hot water supply cycle.

[0031] [Compressor Speed ​​Control] The control device 41 performs compressor speed control in parallel with the cooling operation while the indoor unit 3 is performing cooling operation. In cooling operation, a set temperature is set in the indoor unit 3. For compressor speed control, the control device 41 obtains the set temperature set in the indoor unit 3 and intermittently obtains the room temperature measured by the room temperature sensor 38 from the room temperature sensor 38. The control device 41 calculates the temperature difference based on the room temperature and the set temperature. The temperature difference is equal to the value calculated by subtracting the set temperature from the room temperature.

[0032] The control device 41 calculates a target compressor rotation speed based on the temperature difference and controls the compressor 31 to adjust its rotation speed so that it approaches the target compressor rotation speed. The target compressor rotation speed increases as the temperature difference increases. In other words, the compressor rotation speed of the compressor 31 fluctuates according to the size of the cooling load as the compressor rotation speed control is performed, increasing as the cooling load increases and decreasing as the cooling load decreases.

[0033] When the first cooling and hot water supply mode is running, the control device 41 further calculates a state variable based on the compressor rotation speed adjusted by the compressor rotation speed control. The state variable is a parameter that correlates with the compressor rotation speed and increases as the compressor rotation speed increases; the compressor rotation speed itself may also be used as the state variable. When the first cooling and hot water supply mode is running, the control device 41 further intermittently acquires the inlet water temperature measured by the inlet water temperature sensor 36 from the inlet water temperature sensor 36. As shown in Table 1, the control device 41 runs the first cooling and hot water supply mode when the state variable is within a predetermined range of state variables and the inlet water temperature is above a predetermined inlet water temperature threshold. Here, the predetermined range of state variables is the range of state variables that has been confirmed in advance to be reliable even when operating at high pressure of discharged refrigerant. The inlet water temperature threshold is the upper limit of the inlet water temperature at which it has been confirmed in advance that the discharge pressure of the refrigerant does not rise to the extent that it affects the reliability of the compressor in the low and high ranges of the compressor rotation speed.

[0034] The control device 41 executes the second cooling hot water supply mode when the inlet water temperature is below the inlet water temperature threshold.

[0035] [Second Cooling and Hot Water Supply Mode] In the second cooling and hot water supply mode, the control device 41 controls the compressor 31 and the refrigerant circuit switching valve 32 so that the indoor unit 3 performs cooling operation, similar to the first cooling and hot water supply mode. In the second cooling and hot water supply mode, the control device 41 also performs compressor rotation speed control in parallel with the cooling operation, similar to the first cooling and hot water supply mode.

[0036] In the second cooling and hot water supply mode, the control device 41 controls the switching valve 15 to switch the flow path of the water circuit 6 so that the water refrigerant heat exchanger 14 is connected to the hot water tank 11 via the second inlet 23. The low-temperature water stored in the lower space of the hot water tank 11 is reduced as the pump 12 is driven and flows out of the hot water tank 11 via the outlet 21. The low-temperature water that has flowed out of the hot water tank 11 flows into the water refrigerant heat exchanger 14 via the pump 12. The water refrigerant heat exchanger 14 exchanges heat between the high-pressure gaseous refrigerant that has flowed into the water refrigerant heat exchanger 14 and the low-temperature water that has flowed into the water refrigerant heat exchanger 14, heating the low-temperature water. The low-temperature water is heated in the water refrigerant heat exchanger 14 and becomes high-temperature water. The high-temperature water flows into the hot water tank 11 via the second inlet 23 because the water refrigerant heat exchanger 14 is connected to the second inlet 23 via the switching valve 15. The high-temperature water that flows into the hot water tank 11 via the second inlet 23 is not mixed with the high-temperature water stored in the upper space of the hot water tank 11, but is mixed with the low-temperature water stored in the lower space of the hot water tank 11.

[0037] When the second cooling and hot water supply mode is in operation, the control device 41 intermittently acquires the hot water outlet temperature measured by the hot water outlet temperature sensor 37 from the hot water outlet temperature sensor 37. The control device 41 controls the pump 12 and adjusts the pump rotation speed of the pump 12 so that the hot water outlet temperature approaches the second target hot water outlet temperature. That is, the control device 41 decreases the pump rotation speed when the hot water outlet temperature is lower than the second target hot water outlet temperature, and increases the pump rotation speed when the hot water outlet temperature is higher than the second target hot water outlet temperature. The second target hot water outlet temperature is lower than the first target hot water outlet temperature, and 40°C is an example of the second target hot water outlet temperature.

[0038] In the refrigeration cycle device 1, when the second cooling and hot water supply mode is executed, it is not necessary to raise the pressure saturation temperature of the discharged refrigerant discharged from the compressor 31 of the refrigerant circuit 7 above the first target hot water outlet temperature, and therefore it is not necessary to increase the pressure of the discharged refrigerant. As a result, it is possible to prevent an increase in the load on the compressor shaft and bearings when the compressor rotation speed is low, and to prevent an increase in the load on the sliding parts of the compressor when the compressor rotation speed is high, enabling highly reliable operation. In addition, the refrigeration cycle device 1 can reduce power consumption by reducing the frequency of increasing the pressure of the discharged refrigerant.

[0039] When the second cooling and hot water supply mode is executed, the refrigeration cycle device 1 has a water refrigerant heat exchanger 14 connected to the second inlet 23, which prevents the high-temperature water at the second target hot water output temperature from mixing with the high-temperature water stored in the upper space of the hot water supply tank 11. By preventing the high-temperature water at the second target hot water output temperature from mixing with the high-temperature water stored in the upper space of the hot water supply tank 11, the refrigeration cycle device 1 can prevent the temperature of the high-temperature water stored in the upper space of the hot water supply tank 11 from decreasing. Therefore, the refrigeration cycle device 1 can properly supply hot water to the user so that hot water at a temperature lower than the set hot water supply temperature does not flow out of the faucet.

[0040] The control device 41 executes either the cooling mode or the outside air heat-absorbing hot water supply mode when the state variable is not within a predetermined state variable range and the inlet water temperature is equal to or greater than the inlet water temperature threshold. For example, the control device 41 executes the cooling mode when the state variable is not within a predetermined state variable range, the inlet water temperature is equal to or greater than the inlet water temperature threshold, and the cooling heat demand is greater than the hot water heat demand. The control device 41 executes the outside air heat-absorbing hot water supply mode when the state variable is not within a predetermined state variable range, the inlet water temperature is equal to or greater than the inlet water temperature threshold, and the cooling heat demand is less than the hot water heat demand. Here, for example, the cooling heat demand can be estimated based on the temperature difference between the room temperature and the set temperature, and the hot water demand can be estimated based on the difference between the predicted amount of hot water heat required per day and the current amount of hot water heat.

[0041] [Cooling Mode] In cooling mode, the control device 41 stops the pump 12 to prevent water from circulating in the water circuit 6, controls the refrigerant circuit switching valve 32, and switches the refrigerant circuit 7 to a cooling cycle. In cooling mode, the control device 41 further performs compressor rotation speed control in parallel with the cooling operation, in the same manner as in the first cooling and hot water supply mode. The compressor 31 compresses the low-pressure gas-phase refrigerant sucked into the compressor 31. The low-pressure gas-phase refrigerant is compressed by the compressor 31 and becomes high-pressure gas-phase refrigerant. Since the refrigerant circuit 7 is switched to the cooling cycle, the high-pressure gas-phase refrigerant flows into the outdoor heat exchanger 33.

[0042] The outdoor unit 2 passes outdoor air through the outdoor heat exchanger 33. The outdoor heat exchanger 33 exchanges heat between the high-pressure gas-phase refrigerant flowing into the outdoor heat exchanger 33 and the outdoor air, and cools the high-pressure gas-phase refrigerant flowing into the outdoor heat exchanger 33. The high-pressure gas-phase refrigerant flowing into the outdoor heat exchanger 33 is cooled by the outdoor heat exchanger 33, condenses, and becomes high-pressure liquid-phase refrigerant. That is, the outdoor heat exchanger 33 functions as a condenser when the cooling mode is executed.

[0043] The high-pressure liquid-phase refrigerant flowing out of the outdoor heat exchanger 33 flows into the expansion valve 34. The expansion valve 34 reduces the pressure of the high-pressure liquid-phase refrigerant flowing into the expansion valve 34. The high-pressure liquid-phase refrigerant is decompressed by the expansion valve 34 and becomes low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant flows out of the expansion valve 34 and flows into the indoor heat exchanger 35.

[0044] The indoor unit 3 passes air in the room where the indoor unit 3 is installed through the indoor heat exchanger 35. The indoor heat exchanger 35 exchanges heat between the low-pressure gas-liquid two-phase refrigerant and the air, cools the air, and heats the low-pressure gas-liquid two-phase refrigerant. The indoor unit 3 further blows the air cooled by the indoor heat exchanger 35 into the room. The room where the indoor unit 3 is installed is cooled by the air cooled by the indoor heat exchanger 35 being blown into the room. The low-pressure gas-liquid two-phase refrigerant is heated by the indoor heat exchanger 35, evaporates, and becomes low-pressure gas-phase refrigerant. That is, the indoor heat exchanger 35 functions as an evaporator when the cooling mode is executed. The low-pressure gas-phase refrigerant is sucked into the compressor 31 because the refrigerant circuit 7 is switched to the cooling cycle.

[0045] [Outdoor air heat absorption hot water supply mode] In the outdoor air heat absorption hot water supply mode, the control device 41 controls the switching valve 15 to switch the flow path of the water circuit 6 so that the water refrigerant heat exchanger 14 is connected to the hot water supply tank 11 via the first inlet 22. Driven by the activated pump 12, the low-temperature water stored in the lower space of the hot water supply tank 11 flows out of the hot water supply tank 11 via the outlet 21, and the amount of low-temperature water in the tank decreases. The low-temperature water flowing out of the hot water supply tank 11 flows into the water refrigerant heat exchanger 14. The water refrigerant heat exchanger 14 causes heat exchange between the high-pressure gaseous refrigerant that has flowed into the water refrigerant heat exchanger 14 and the low-temperature water supplied from the pump 12, thereby heating the low-temperature water. The low-temperature water is heated by the water refrigerant heat exchanger 14 to become high-temperature water. Since the water refrigerant heat exchanger 14 is connected to the first inlet 22 via the switching valve 15, the high-temperature water flows into the upper space of the hot water supply tank 11 via the first inlet 22. The high-temperature water heated by the water refrigerant heat exchanger 14 flows into the upper space of the hot water supply tank 11, mixes with the high-temperature water originally stored in the upper space of the hot water supply tank 11, and increases the amount of high-temperature water stored therein.

[0046] When the outdoor air heat absorption hot water supply mode is being executed, the control device 41 intermittently acquires the hot water discharge temperature measured by the hot water discharge temperature sensor 37 from the hot water discharge temperature sensor 37. The control device 41 decreases the pump rotation speed when the hot water discharge temperature is lower than the first target hot water discharge temperature, and increases the pump rotation speed when the hot water discharge temperature is higher than the first target hot water discharge temperature.

[0047] In the outdoor air heat absorption hot water supply mode, the control device 41 controls the refrigerant circuit switching valve 32 to switch the refrigerant circuit 7 to the outdoor air heat absorption hot water supply cycle. In the outdoor air heat absorption hot water supply mode, the control device 41 executes compressor rotation speed control such that the compressor 31 is driven at a predetermined predetermined compressor rotation speed. The compressor 31 compresses the low-pressure gaseous refrigerant sucked into the compressor 31. The low-pressure gaseous refrigerant is compressed by the compressor 31 to become a high-pressure gaseous refrigerant. Since the refrigerant circuit 7 has been switched to the outdoor air heat absorption hot water supply cycle, the high-pressure gaseous refrigerant flows into the water refrigerant heat exchanger 14.

[0048] The water-refrigerant heat exchanger 14 exchanges heat between the high-pressure gaseous refrigerant flowing into the water-refrigerant heat exchanger 14 and the low-temperature water flowing into the water-refrigerant heat exchanger 14, thereby cooling the high-pressure gaseous refrigerant flowing into the water-refrigerant heat exchanger 14. The high-pressure gaseous refrigerant flowing into the water-refrigerant heat exchanger 14 is cooled and condensed by the water-refrigerant heat exchanger 14, becoming a high-pressure liquid-phase refrigerant. In other words, the water-refrigerant heat exchanger 14 functions as a condenser when the outside air heat intake hot water supply mode is executed.

[0049] The high-pressure liquid-phase refrigerant flows out of the water refrigerant heat exchanger 14 and into the expansion valve 34. The expansion valve 34 reduces the pressure of the high-pressure liquid-phase refrigerant that has flowed into it. The high-pressure liquid-phase refrigerant is reduced in pressure by the expansion valve 34 and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant flows out of the expansion valve 34 and into the outdoor heat exchanger 33.

[0050] The outdoor unit 2 allows outside air to pass through the outdoor heat exchanger 33. The outdoor heat exchanger 33 exchanges heat between the low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 33 and the outside air, heating the low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 33. The low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 33 is heated by the outdoor heat exchanger 33, evaporates, and becomes low-pressure gaseous refrigerant. In other words, the outdoor heat exchanger 33 functions as an evaporator when the outside air heat absorption hot water supply mode is executed. The low-pressure gaseous refrigerant is drawn into the compressor 31 because the refrigerant circuit 7 has switched to the outside air heat absorption hot water supply cycle.

[0051] When the first cooling and hot water supply mode or the second cooling and hot water supply mode is executed, the indoor unit 3 performs cooling operation while water circulates through the water circuit 6. When the cooling mode is executed, the indoor unit 3 performs cooling operation without water circulating through the water circuit 6. When the outside air heat absorption and hot water supply mode is executed, the indoor unit 3 does not perform cooling operation while water circulates through the water circuit 6. In other words, when the indoor unit 3 performs cooling operation while water circulates through the water circuit 6, either the first cooling and hot water supply mode or the second cooling and hot water supply mode is executed.

[0052] [Summary of the Refrigeration Cycle Device 1 of Example 1] The refrigeration cycle device 1 of Example 1 comprises a refrigerant circuit 7, a water circuit 6, a pump 12, an indoor unit 3, a hot water outlet temperature sensor 37, and a control device 41. Refrigerant circulates through the refrigerant circuit 7. The water circuit 6 comprises a water-refrigerant heat exchanger 14 that exchanges heat between refrigerant and water, and a hot water supply tank 11. The pump 12 circulates water through the water circuit 6 so that low-temperature water is supplied from the outlet 21 of the hot water supply tank 11 to the water-refrigerant heat exchanger 14, and high-temperature water, heated in the water-refrigerant heat exchanger 14, is supplied from the water-refrigerant heat exchanger 14 to the hot water supply tank 11. The indoor unit 3 performs cooling operation. The hot water outlet temperature sensor 37 measures the temperature of the high-temperature water as the hot water outlet temperature. The control device 41 executes either a first cooling hot water supply mode or a second cooling hot water supply mode when the indoor unit 3 circulates water through the water circuit 6 while performing cooling operation. In the first cooling and hot water supply mode, the control device 41 controls the pump 12 so that the hot water temperature approaches the first target hot water temperature. In the second cooling and hot water supply mode, the control device 41 controls the pump 12 so that the hot water temperature approaches the second target hot water temperature, which is lower than the first target hot water temperature.

[0053] In the refrigeration cycle device 1 of Example 1, when the second cooling and hot water supply mode is executed, it is not necessary to raise the pressure saturation temperature of the discharged refrigerant discharged from the compressor 31 of the refrigerant circuit 7 above the first target hot water outlet temperature, and therefore it is not necessary to increase the pressure of the discharged refrigerant. For this reason, the refrigeration cycle device 1 of Example 1 can operate with high reliability even when the compressor rotation speed is low or high, for example, when the second cooling and hot water supply mode is executed. In addition, the refrigeration cycle device 1 of Example 1 can reduce power consumption by reducing the frequency of increasing the pressure of the discharged refrigerant.

[0054] The refrigeration cycle device 1 of Example 1 is further equipped with an inlet water temperature sensor 36 that measures the temperature of low-temperature water as the inlet water temperature. The control device 41 executes the first cooling hot water supply mode when the inlet water temperature is above the inlet water temperature threshold, and executes the second cooling hot water supply mode when the inlet water temperature is below the inlet water temperature threshold. When the inlet water temperature is high, the outlet water temperature tends to be high. For this reason, if the target outlet water temperature is set low when the inlet water temperature is high, it may be necessary to take measures such as excessively increasing the rotation speed of the pump 12, which may increase power consumption. Alternatively, even if the rotation speed of the pump 12 is increased to the maximum, it may not be possible to bring the outlet water temperature close to the target outlet water temperature. In the refrigeration cycle device 1 of Example 1, the second cooling exhaust heat hot water supply mode is executed when the inlet water temperature is low, which allows the pressure of the discharged refrigerant to be lowered without excessively increasing the rotation speed of the pump 12, thereby achieving both improved reliability and reduced power consumption.

[0055] The refrigeration cycle device 1 of Embodiment 1 further includes a compressor 31 that circulates refrigerant in a flow rate corresponding to the compressor rotation speed through the refrigerant circuit 7. The control device 41 controls the indoor unit 3 and the pump 12 so that a cooling mode or an outside air heat-absorbing hot water supply mode is executed when a state variable correlated with the compressor rotation speed is not included in a predetermined state variable range and the inlet water temperature is equal to or greater than the inlet water temperature threshold. In cooling mode, the control device 41 controls the indoor unit 3 and the pump 12 so that cooling operation is performed without circulating water through the water circuit 6. In outside air heat-absorbing hot water supply mode, the control device 41 controls the indoor unit 3 and the pump 12 so that water is circulated through the water circuit 6 without performing cooling operation.

[0056] When the inlet water temperature is high, it is difficult to lower the target outlet water temperature, and it is necessary to operate the system with a high pressure saturation temperature for the discharged refrigerant. When the state quantity is outside the predetermined state quantity range, if the system operates with a high pressure saturation temperature for the discharged refrigerant, the pressure of the discharged refrigerant will rise, and the reliability of the compressor 31 may not be ensured. The refrigeration cycle device 1 of Example 1 can ensure reliability by operating with a low discharged refrigerant pressure, even when the user requests both cooling operation and hot water supply simultaneously, by not executing the first cooling-hot water supply mode and the second cooling-hot water supply mode.

[0057] The control device 41 of the refrigeration cycle device 1 in Example 1 executes the first cooling and hot water supply mode when the state quantity is within a predetermined state quantity range and the inlet water temperature is above the inlet water temperature threshold. When the state quantity is within the predetermined state quantity range, there is no problem with the reliability of the compressor 31 even if operation with a high discharge refrigerant pressure is performed. The refrigeration cycle device 1 in Example 1 can appropriately satisfy the hot water supply requirement in a way that ensures the reliability of the compressor 31 by executing the first cooling and hot water supply mode when the state quantity is within a predetermined state quantity range and the inlet water temperature is above the inlet water temperature threshold.

[0058] The refrigeration cycle device 1 of Embodiment 1 further includes a switching valve 15 connected to a water refrigerant heat exchanger 14. The hot water tank 11 has a first inlet 22 and a second inlet 23. The first inlet 22 is located at the top of the hot water tank 11 and connected to the switching valve 15. The second inlet 23 is located below the first inlet 22 and connected to the switching valve 15. The control device 41 controls the switching valve 15 so that high-temperature water is supplied to the hot water tank 11 via the first inlet 22 when the first cooling hot water mode is performed. The control device 41 controls the switching valve 15 so that high-temperature water is supplied to the hot water tank 11 via the second inlet 23 when the second cooling hot water mode is performed.

[0059] When water with a lower temperature than the hot water stored in the upper space of the hot water supply tank 11 flows into the upper space of the hot water supply tank 11 via the first inlet 22, the temperature of the hot water supplied to the user may decrease. The refrigeration cycle device 1 of Embodiment 1 can prevent the temperature of the hot water stored in the upper space of the hot water supply tank 11 from decreasing by allowing hot water with a second target hot water output temperature to flow into the intermediate part between the upper and lower spaces of the hot water supply tank 11 via the second inlet 23.

[0060] Incidentally, although the state variables in the refrigeration cycle device 1 of the previously described embodiment 1 are calculated based on the compressor rotation speed, they may also be calculated based on values ​​other than the compressor rotation speed. Examples of such values ​​include the temperature difference calculated by subtracting the set temperature from the room temperature, and the temperature of the discharged refrigerant discharged from the compressor 31. Even in this case, the state variables correlate with the compressor rotation speed, and the refrigeration cycle device can reduce power consumption and improve the reliability of the compressor 31, similar to the refrigeration cycle device 1 of the previously described embodiment 1.

[0061] Incidentally, the refrigeration cycle device 1 of the previously described embodiment 1 executes the second cooling and hot water supply mode when the state quantity is within a predetermined state quantity range and the inlet water temperature is below the inlet water temperature threshold. However, the first cooling and hot water supply mode may also be executed. In this case, the refrigeration cycle device consumes more power than the refrigeration cycle device 1 of the previously described embodiment 1 because the pressure of the discharged refrigerant increases. However, since the state quantity is within a predetermined state quantity range, there is no problem with the reliability of the compressor 31. Therefore, when it is more important to satisfy the hot water supply requirement than to consume power, executing the first cooling and hot water supply mode is effective.

[0062] Incidentally, the refrigeration cycle device 1 of the previously described embodiment 1 operates in cooling mode when the state quantity is outside the predetermined state quantity range, the inlet water temperature is above the inlet water temperature threshold, and the heat demand for cooling is greater than the heat demand for hot water supply, but it may also operate in cooling mode. In this case as well, the refrigeration cycle device can operate at a low discharge refrigerant pressure, similar to the refrigeration cycle device 1 of the previously described embodiment 1, and the reliability of the compressor 31 can be ensured.

[0063] Incidentally, the refrigeration cycle device 1 of the previously described embodiment 1 executes a mode selected based on the state variable and the inlet water temperature from among the first cooling hot water supply mode and the second cooling hot water supply mode, but it may also execute a mode selected based on other conditions. For example, the refrigeration cycle device may execute the first cooling hot water supply mode when the outlet water temperature measured by the outlet water temperature sensor 37 is equal to or greater than the outlet water temperature threshold, and execute the second cooling hot water supply mode when the outlet water temperature is less than the outlet water temperature threshold. Even in this case, the refrigeration cycle device can reduce power consumption and improve the reliability of the compressor 31, similar to the refrigeration cycle device 1 of the previously described embodiment 1.

[0064] Although examples have been described above, the examples are not limited to those described above. Furthermore, the components described above include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are equivalent. Moreover, the components described above can be combined as appropriate. Furthermore, at least one of the various omissions, substitutions, and modifications of the components can be made without departing from the gist of the examples.

[0065] 1: Refrigeration cycle unit 3: Indoor unit 6: Water circuit 7: Refrigerant circuit 11: Hot water tank 12: Pump 14: Water-refrigerant heat exchanger 15: Switching valve 21: Outlet 22: First inlet 23: Second inlet 31: Compressor 33: Outdoor heat exchanger 36: Inlet water temperature sensor 37: Outlet water temperature sensor 41: Control device

Claims

1. A refrigeration cycle device comprising: a water circuit having a refrigerant circuit through which a refrigerant circulates; a water refrigerant heat exchanger that exchanges heat between the refrigerant and water; a water supply tank; a pump that circulates water in the water circuit such that low-temperature water is supplied from the outlet of the water supply tank to the water refrigerant heat exchanger, and high-temperature water, which is heated in the water refrigerant heat exchanger, is supplied from the water refrigerant heat exchanger to the water supply tank; an indoor unit that performs cooling operation; a hot water outlet temperature sensor that measures the temperature of the high-temperature water as the hot water outlet temperature; and a control device that executes one of the following modes: a first cooling hot water supply mode that controls the pump so that the hot water outlet temperature approaches a first target hot water outlet temperature when the indoor unit circulates water in the water circuit while performing cooling operation; and a second cooling hot water supply mode that controls the pump so that the hot water outlet temperature approaches a second target hot water outlet temperature which is lower than the first target hot water outlet temperature.

2. The refrigeration cycle apparatus according to claim 1, further comprising an inlet water temperature sensor that measures the temperature of the low-temperature water as the inlet water temperature, wherein the control device executes the first cooling hot water supply mode when the inlet water temperature is equal to or greater than the inlet water temperature threshold, and executes the second cooling hot water supply mode when the inlet water temperature is less than the inlet water temperature threshold.

3. The refrigeration cycle apparatus according to claim 2, further comprising a compressor that circulates a refrigerant in a flow rate corresponding to the compressor rotation speed through the refrigerant circuit, wherein the control device controls the indoor unit and the pump to perform cooling operation without circulating water through the water circuit, or to circulate water through the water circuit without performing cooling operation, when a state quantity correlated with the compressor rotation speed is not included in a predetermined state quantity range and the inlet water temperature is equal to or greater than the inlet water temperature threshold.

4. The refrigeration cycle apparatus according to claim 3, wherein the control device executes the first cooling hot water supply mode when the state quantity is within the predetermined state quantity range and the inlet water temperature is equal to or greater than the inlet water temperature threshold.

5. The refrigeration cycle apparatus according to claim 1, further comprising a switching valve connected to the water refrigerant heat exchanger, wherein the hot water tank has a first inlet located at the top of the hot water tank and connected to the switching valve, and a second inlet located below the first inlet and connected to the switching valve, and the control device controls the switching valve so that when the first cooling hot water mode is performed, the high-temperature water is supplied to the hot water tank via the first inlet, and when the second cooling hot water mode is performed, the switching valve is controlled so that the high-temperature water is supplied to the hot water tank via the second inlet.

6. The refrigeration cycle apparatus according to claim 1, wherein the control device executes the first cooling hot water supply mode when the hot water outlet temperature is equal to or greater than the hot water outlet temperature threshold, and executes the second cooling hot water supply mode when the hot water outlet temperature is less than the hot water outlet temperature threshold.

Images