JP2024061161A - Hot water storage and heating equipment - Google Patents

Abstract

A hot water storage and heating device is provided that can reduce the excessive operating load on a compressor of a heat pump unit during a defrosting operation. [Solution] A hot water storage and heating device (1) including a heat pump unit (4) formed by connecting a compressor (21), a condensing heat exchanger (22), an expansion valve (23), and an evaporative heat exchanger (24) by a refrigerant circuit (25), a hot water storage tank (2), and a control unit (18) for controlling a hot water storage operation in which hot water heated by the heat pump unit (4) is stored in the hot water storage tank (2), the device includes a discharge temperature detection means (26) for detecting the discharge temperature of the refrigerant of the compressor (21), and an evaporative heat exchange outlet temperature detection means (27) for detecting the refrigerant temperature at the outlet of the evaporative heat exchanger (24). When the control unit (18) detects frost on the evaporative heat exchanger (24) based on the refrigerant temperature at the outlet of the evaporative heat exchanger (24) during the hot water storage operation, the control unit (18) starts a defrosting operation to remove the frost, and when it detects an increase in the discharge temperature during the defrosting operation after a predetermined time has elapsed since the start of the defrosting operation, the control unit (18) reduces the operating speed of the compressor (21). [Selected Figure] Fig. 4

Description

The present invention relates to a hot water storage and hot water supply system that uses hot water heated by a heat pump unit and stored in a hot water storage tank for hot water supply, and in particular to a defrosting operation of the heat pump unit that is performed during hot water storage operation.

Conventionally, hot water storage and hot water supply systems have been widely used, which perform hot water storage operation to store hot water heated by a heat pump unit in a hot water storage tank and use this stored hot water for hot water supply. The heat pump unit is composed of a compressor, a condensing heat exchanger, an expansion valve, and an evaporating heat exchanger connected by a refrigerant circuit.

In hot water storage operation, the heat of the outside air is absorbed by the refrigerant in the evaporative heat exchanger, and the heat of this refrigerant is used to heat hot water. Therefore, when the outside temperature is low, the moisture contained in the outside air that has absorbed heat and dropped in temperature condenses, making it more likely for frost to form on the evaporative heat exchanger. Since frost on the evaporative heat exchanger prevents the absorption of heat from the outside air, when frost is detected, a defrosting operation is performed to remove the frost.

Regarding this defrosting operation, for example, Patent Document 1 discloses a hot water storage and hot water supply device that switches the connection of the refrigerant circuit to reverse the flow direction of the refrigerant and circulates the high-temperature refrigerant discharged from the compressor through the evaporative heat exchanger to perform the defrosting operation. Also, for example, Patent Document 2 discloses a hot water storage and hot water supply device that is equipped with a heater that warms outside air and performs a defrosting operation by blowing the outside air warmed by the heater through the evaporative heat exchanger to melt the frost.

Patent No. 5333597 JP 2008-57910 A

In the defrosting operation of Patent Document 1, the operating speed (frequency) of the compressor is reduced or stopped in order to switch the connection of the refrigerant circuit, and the operating speed during defrosting operation that is preset after the connection is switched is set. Therefore, it takes time for the high-temperature refrigerant to circulate through the evaporative heat exchanger, and there is a risk that the time required for the defrosting operation will be long. In addition, it also takes time to switch the connection of the refrigerant circuit and resume the hot water storage operation after the defrosting operation is completed, and there is a risk that the time required for the hot water storage operation will be long.

On the other hand, the defrosting operation of Patent Document 2 is not preferable because the heater for warming the outside air complicates the hot water storage and hot water supply device, increasing manufacturing costs. Therefore, defrosting operation is often performed by stopping the flow of hot water supplied from the hot water storage tank to the condensing heat exchanger, opening the expansion valve to a specified degree, and circulating the high-temperature refrigerant discharged from the compressor through the evaporative heat exchanger without switching the connection of the refrigerant circuit to remove frost.

However, during this defrosting operation, the liquefied refrigerant may impede the flow of refrigerant in the refrigerant circuit, placing an excessive operating load on the compressor. For example, in the expansion valve, the liquefied refrigerant may impede the flow of gaseous refrigerant, causing the discharge pressure of the compressor to rise and increasing the operating load. There is concern that the excessive operating load during this defrosting operation may cause the compressor to deteriorate in durability or break.

The present invention aims to provide a hot water storage and hot water supply device that can reduce excessive operating load on the compressor of a heat pump unit during defrosting operation.

The hot water storage and hot water supply device of the invention of claim 1 includes a heat pump unit formed by connecting a compressor, a condensing heat exchanger, an expansion valve, and an evaporative heat exchanger by a refrigerant circuit, a hot water storage tank, and a control unit that controls a hot water storage operation in which hot water heated by the heat pump unit is stored in the hot water storage tank. The device is equipped with a discharge temperature detection means that detects the discharge temperature of the refrigerant of the compressor, and an evaporative heat exchange outlet temperature detection means that detects the refrigerant temperature at the outlet of the evaporative heat exchanger. The control unit starts a defrosting operation to remove the frost when it detects frost on the evaporative heat exchanger based on the refrigerant temperature at the outlet of the evaporative heat exchanger during the hot water storage operation, and reduces the operating speed of the compressor when it detects an increase in the discharge temperature during the defrosting operation after a predetermined time has elapsed since the start of the defrosting operation.

According to the above configuration, the hot water storage and hot water supply device stores hot water heated by the heat pump unit in the hot water storage tank, and when frost formation on the evaporative heat exchanger of the heat pump unit is detected during this hot water storage operation, a defrosting operation is started to remove the frost. Then, when an increase in the discharge temperature of the refrigerant discharged by the compressor is detected during the defrosting operation after a predetermined time has elapsed since the start of the defrosting operation, the operating speed of the compressor is reduced. Since the increase in the discharge temperature of the refrigerant discharged by the compressor during the defrosting operation is caused by an increase in the discharge pressure and indicates an increase in the operating load of the compressor, the operating speed of the compressor can be reduced to reduce the increase in the operating load. Therefore, the excessive operating load on the compressor of the heat pump unit during the defrosting operation can be reduced, and deterioration of the durability or damage to the compressor can be prevented.

The hot water storage and hot water supply device of the present invention according to claim 2 is the first invention, characterized in that the control unit sets a range of decrease in the operating rotation speed in accordance with a range of increase in the discharge temperature.
According to the above configuration, the reduction range of the operating speed of the compressor is set in accordance with the increase range of the compressor discharge temperature, so that the operating speed can be reduced in response to an increase in the operating load of the compressor, thereby mitigating the increase in the operating load.

The hot water storage and hot water supply device of the invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the control unit, when it detects a decrease in the discharge temperature after reducing the operating speed, increases the operating speed by setting an increase in the operating speed according to the decrease in the discharge temperature.
According to the above configuration, when a drop in the discharge temperature of the compressor is detected after the operating load of the compressor is reduced, the increase range of the operating speed of the compressor is set corresponding to the drop range of the discharge temperature, and the operating speed of the compressor is increased. The drop in the discharge temperature of the refrigerant discharged from the compressor after the operating speed is reduced is due to a drop in the discharge pressure of the compressor, and since the operating load of the compressor is reduced, the operating speed of the compressor is increased to approach the state before the reduction in the operating speed. Therefore, after the excessive operating load on the compressor of the heat pump unit during the defrosting operation is no longer imposed, the operating speed is brought close to the operating speed at the start of the defrosting operation, so that the time required for the defrosting operation can be prevented from becoming long.

The hot water storage and hot water supply device of the present invention can reduce the excessive operating load on the compressor of the heat pump unit during defrosting operation.

1 is an explanatory diagram of a hot water storage and heating device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of the heat pump unit of FIG. 1 . 4 is a flowchart of hot water storage operation control. 4 is a flowchart of a defrosting operation control. 13 is an example of data showing fluctuations in the discharge temperature and discharge pressure of the compressor, the refrigerant temperature at the outlet of the expansion valve, and the refrigerant temperature at the outlet of the evaporative heat exchanger during a defrosting operation.

The following describes the form for implementing the present invention based on examples.

First, the configuration of the hot water storage and supplying apparatus 1 of the present invention will be described.
As shown in Fig. 1, the hot water storage and hot water supply device 1 has a hot water storage unit 3 equipped with a hot water storage tank 2, a heat pump unit 4, and, for example, a combustion-type auxiliary heat source device 5. This hot water storage and hot water supply device 1 performs a hot water storage operation in which hot water heated to a predetermined target hot water storage temperature by the heat pump unit 4 is stored in the hot water storage tank 2. The auxiliary heat source device 5 supplies the hot water discharged from the hot water storage unit 3 to the hot water supply tap 6 either heated or unheated depending on the temperature of the hot water, in order to supply hot water at a hot water supply setting temperature from the hot water supply tap 6 as shown by the arrow HW.

Next, the hot water storage unit 3 will be described.
A supply passage 8 equipped with a hot water storage pump 7 is connected to the bottom of the hot water storage tank 2 in order to supply hot water from the hot water storage tank 2 to the heat pump unit 4. A return passage 9 is connected to the top of the hot water storage tank 2 in order to store the hot water heated by the heat pump unit 4 in the hot water storage tank 2. A changeover valve 10 for switching the flow path of the hot water is disposed midway through the return passage 9, and a return branch passage 9a branched off from the return passage 9 at this changeover valve 10 is connected to a portion of the supply passage 8 upstream of the hot water storage pump 7.

A return temperature sensor 9b is disposed upstream of the switching valve 10 in the return passage 9 to detect the temperature of the hot water heated by the heat pump unit 4. For example, if the temperature detected by the return temperature sensor 9b immediately after starting the heat pump unit 4 is lower than a predetermined hot water set temperature, the switching valve 10 can be switched from the hot water tank 2 side to the return branch passage 9a side to circulate the hot water without returning it to the hot water tank 2 until it can be heated sufficiently.

A water supply passage 11 that supplies clean water, as indicated by the arrow CW, is connected to the bottom of the hot water storage tank 2. A hot water outlet passage 12 that allows the hot water in the hot water storage tank 2 to be discharged from the hot water storage unit 3 is connected to the top of the hot water storage tank 2. A mixing valve 14 is provided midway along the hot water outlet passage 12, and a water supply branch passage 11a that branches off from midway along the water supply passage 11 is connected to the mixing valve 14. The hot water from the hot water storage tank 2 and the clean water from the water supply branch passage 11a are mixed by the mixing valve 14 and discharged from the hot water storage unit 3.

The hot water storage tank 2 has multiple hot water temperature sensors 2a-2d arranged at a predetermined interval in the vertical direction, which can detect the temperature of the hot water stored in the hot water storage tank 2 and the amount of hot water stored at that temperature. In order to prevent the temperature of the stored hot water from dropping, insulation material (not shown) is arranged to cover the hot water temperature sensors 2a-2d and the hot water storage tank 2.

A water supply temperature sensor 11b is provided in the water supply passage 11 to detect the temperature (water supply temperature) of the clean water flowing through the water supply passage 11. A water outlet flow rate sensor 12a is provided in the hot water outlet passage 12 to detect the hot water outlet flow rate from the hot water storage unit 3, a hot water storage tank outlet water temperature sensor 12b is provided in the hot water outlet passage 12 to detect the temperature of the hot water that is discharged from the hot water storage tank 2 and supplied to the mixing valve 14, and an outlet water temperature sensor 12c is provided in the hot water outlet passage 12 to detect the hot water outlet temperature from the hot water storage unit 3. The hot water outlet passage 12 is connected to the water supply port 5a of the auxiliary heat source unit 5 by a hot water passage 15, and the hot water supply port 5b of the auxiliary heat source unit 5 is connected to the hot water tap 6 by a hot water passage 16.

The hot water storage unit 3 has a hot water storage unit control unit 18 (control unit) that, for example, controls the hot water storage operation and controls the temperature adjustment of the hot water discharged from the hot water storage unit 3. The hot water storage unit control unit 18 drives the heat pump unit 4 and the hot water storage pump 7 to perform hot water storage operation in which hot water heated by the heat pump unit 4 is stored from the top of the hot water storage tank 2. When the hot water outlet flow rate sensor 12a detects a flow rate equal to or greater than a predetermined flow rate, the mixing ratio of the mixing valve 14 is adjusted based on the temperatures detected by the water supply temperature sensor 11b and the hot water storage tank outlet temperature sensor 12b, and hot water is discharged so that the temperature detected by the outlet temperature sensor 12c becomes the predetermined outlet temperature.

An operation terminal 19 is connected to the hot water storage unit control unit 18 and the auxiliary heat source unit 5, for example, so that the hot water supply user can set the hot water supply setting temperature, etc. A plurality of operation terminals 19 may be connected, and an operation terminal 19 corresponding to the hot water storage unit 3 may be connected to the hot water storage unit control unit 18, and an operation terminal corresponding to the auxiliary heat source unit 5 may be connected to the auxiliary heat source unit 5.

Next, the heat pump unit 4 will be described.
2, the heat pump unit 4 is configured by connecting a compressor 21, a condensing heat exchanger 22, an expansion valve 23, and an evaporative heat exchanger 24 by a refrigerant circuit 25. The refrigerant circuit 25 is filled with refrigerant that passes through the compressor 21, the condensing heat exchanger 22, the expansion valve 23, and the evaporative heat exchanger 24. The refrigerant circuit 25 is provided with a discharge temperature sensor 26 (discharge temperature detection means) that detects the temperature of the refrigerant discharged from the compressor 21, and an evaporative heat exchanger outlet temperature sensor 27 (evaporative heat exchanger outlet temperature detection means) that detects the refrigerant temperature at the outlet of the evaporative heat exchanger 24.

The heat pump unit 4 includes a blower fan 28 that sends outside air to the evaporative heat exchanger 24, and a heat pump unit control unit 29 that controls the heat pump unit 4 based on commands from the hot water storage unit control unit 18. The heat pump unit control unit 29 acquires the detected temperatures of the discharge temperature sensor 26 and the evaporative heat exchange outlet temperature sensor 27, communicates with the hot water storage unit control unit 18 via a communication line 29a, and controls the operating speed of the compressor 21, the opening of the expansion valve 23, and the air flow rate of the blower fan 28.

The compressor 21 supplies the compressed, high-temperature, high-pressure refrigerant to the condensing heat exchanger 22. In the condensing heat exchanger 22, the hot water in the hot water storage tank 2 supplied by the hot water storage pump 7 is heated to the target hot water storage temperature by heat exchange with the high-temperature refrigerant and returned to the hot water storage tank 2. The high-pressure refrigerant whose temperature has been reduced by heat exchange in the condensing heat exchanger 22 is sent to the expansion valve 23.

The expansion valve 23 is a control valve whose throttle amount can be changed by driving an electric motor, for example. The high-pressure refrigerant sent to this expansion valve 23 expands rapidly as it passes through the expansion valve 23, becoming colder than the outside air, and is sent to the evaporation heat exchanger 24. The refrigerant, whose temperature has increased as it absorbs heat from the outside air blown by the blower fan 28 in the evaporation heat exchanger 24, returns to the compressor 21, where it is compressed again and becomes hot again.

Next, the hot water storage operation and the defrosting operation carried out during this hot water storage operation will be described.
The hot water storage unit control unit 18 learns and stores the time of hot water use, the amount of use, etc. as a hot water use history, and predicts the start time of future hot water use, the amount of use, etc. based on this hot water use history. Then, it performs a hot water storage operation to store the amount of heat required equivalent to the predicted amount of use until the predicted hot water use start time. The control of this hot water storage operation will be described based on the flowchart in Figure 3. In the figure, Si (i = 1, 2, ...) represents a step.

When hot water storage operation control is started, in S1, hot water storage operation at a target hot water storage temperature is started based on the prediction of hot water use, and the process proceeds to S2. Specifically, the heat pump unit 4 is operated and the hot water storage pump 7 is driven. The heat pump unit 4 drives the blower fan 28, drives the compressor 21 at a predetermined operating speed, opens the expansion valve 23 to a predetermined degree to cause the refrigerant in the refrigerant circuit 25 to flow, and heats the hot water from the hot water storage tank 2 in the condensing heat exchanger 22.

In S2, it is determined whether or not the storage of the required amount of heat at the target hot water storage temperature has been completed. If the determination in S2 is Yes, the process proceeds to S3, where the hot water storage operation is terminated and hot water storage operation control is terminated. On the other hand, if the determination in S2 is No, the process proceeds to S4, where it is determined whether or not frost has formed on the evaporative heat exchanger 24 based on fluctuations in the refrigerant temperature at the outlet of the evaporative heat exchanger 24. This frost determination utilizes the fact that after some time has passed since the start of hot water storage operation, frost has formed on the evaporative heat exchanger 24, making it difficult for the refrigerant to absorb heat from the outside air, causing the refrigerant temperature at the outlet of the evaporative heat exchanger 24 to drop. If the determination in S4 is No, the process returns to S2 and the hot water storage operation continues.

On the other hand, if the determination in S4 is Yes, the process proceeds to S5, where the hot water storage pump 7 is stopped to interrupt the hot water storage operation, and the process proceeds to S6. Then, in S6, defrosting operation control is performed. Since frost on the evaporative heat exchanger 24 prevents the refrigerant from absorbing heat from the outside air and reduces the efficiency of the hot water storage operation, a defrosting operation is performed to remove the frost on the evaporative heat exchanger 24 so that the hot water storage operation can be performed efficiently.

As shown in FIG. 4, the defrost operation control first proceeds to S11, where the blower fan 28 is stopped, the expansion valve 23 is set to the defrost opening, and the operating speed of the compressor 21 is changed to the defrost speed (e.g., 75 rpm), and then the process proceeds to S12.

In S12, the refrigerant temperature at the outlet of the evaporative heat exchanger 24 and the discharge temperature of the compressor 21 are obtained, and the process proceeds to S13. In S13, it is determined whether the refrigerant temperature at the outlet of the evaporative heat exchanger 24 to be defrosted has reached or exceeded a predetermined required defrost temperature. This is a step for determining whether defrosting has been completed. When the frost on the evaporative heat exchanger 24 is removed, the heat emitted from the refrigerant decreases and the refrigerant temperature at the outlet of the evaporative heat exchanger 24 rises from, for example, 0°C. If the temperature of this refrigerant reaches or exceeds a preset required defrost temperature (for example, 5°C) and the determination in S13 is Yes, the defrosting is completed, so the process proceeds to S14, the defrosting operation is terminated in S14, the process returns, and the process proceeds to S7 in FIG. 3. Then, in S7, the hot water storage operation is resumed from the state in which the hot water storage operation was interrupted, and the process returns to S2. If the determination in S2 is Yes, the process proceeds to S3, the hot water storage operation is terminated in S3, and the hot water storage operation control is terminated.

On the other hand, if the determination in S13 in FIG. 4 is No, the defrosting operation continues and proceeds to S15, where it is determined whether or not a predetermined time has elapsed since the start of the defrosting operation. FIG. 5 shows an example of experimentally recorded changes in the refrigerant discharge temperature and discharge pressure of the compressor 21 during defrosting operation, the refrigerant temperature at the outlet of the expansion valve 23, and the refrigerant temperature at the outlet of the evaporative heat exchanger 24. The solid line L1 is the refrigerant discharge temperature of the compressor 21, the dashed line L2 is the refrigerant discharge pressure of the compressor 21, the solid line L3 is the refrigerant temperature at the outlet of the expansion valve 23, and the solid line L4 is the refrigerant temperature at the outlet of the evaporative heat exchanger 24.

When the defrosting operation is started at time t0 during the hot water storage operation, the discharge pressure and discharge temperature fluctuate due to the change in the operating speed of the compressor 21 and the drive of the expansion valve 23, and the temperature of the refrigerant at the outlet of the expansion valve 23 and the outlet of the evaporative heat exchanger 24 fluctuate. In FIG. 5, the discharge pressure drops once from the hot water storage operation, then gradually rises until it becomes higher than the hot water storage operation, and after time t1, it stabilizes at about 2 MPa. In addition, the discharge temperature drops more than during the hot water storage operation, and after time t1, the decrease in the discharge temperature becomes gradual. The refrigerant temperature at the outlet of the expansion valve 23 becomes lower once compared to the hot water storage operation, then rises to about 25°C in response to the increase in discharge pressure, and after time t1, it stabilizes approximately. The refrigerant temperature at the outlet of the evaporative heat exchanger 24 is initially lower than during hot water storage operation because there is almost no heat exchange with the outside air and heat is released to melt the frost, but the temperature of the refrigerant supplied from the expansion valve 23 rises, so it rises to about 0°C and stabilizes after time t1.

The time required for this stabilization is set as the predetermined time, and for example, the time from time t0 to time t1 corresponds to the predetermined time. If the judgment in S15 in FIG. 4 is No, the process returns to S12. If the judgment in S15 is Yes, the process proceeds to S16, where it is judged whether the discharge temperature of the refrigerant of the compressor 21 has started to rise. Here, at time t2 during the defrosting operation in FIG. 5, for example, liquefied refrigerant blocks the expansion valve 23, so that the high-temperature, high-pressure gas refrigerant cannot pass through the expansion valve 23, and the outlet temperature of the expansion valve 23 drops sharply. This causes the discharge pressure and discharge temperature of the compressor 21 to rise. After a while, the blockage caused by the liquefied refrigerant is naturally eliminated by being washed away by the high-temperature, high-pressure refrigerant or vaporized, and at time t3, the discharge pressure and discharge temperature of the compressor 21 start to drop and the outlet temperature of the expansion valve 23 starts to recover.

However, during that time, the discharge pressure of the compressor 21 is higher than the stable discharge pressure up to time t1, and an excessive operating load is placed on the compressor 21, which may cause a deterioration in durability or failure of the compressor 21. Therefore, in order to reduce the excessive operating load on the compressor 21 caused by this temporary blockage, the defrosting operation is controlled to reduce the operating load when the discharge temperature begins to rise as the stable discharge pressure increases.

If the determination in S16 in FIG. 4 is No, the compressor 21 is not in an excessively loaded state, and the process returns to S12. On the other hand, if the determination in S16 is Yes, the compressor 21 is in an excessively loaded state, and the process proceeds to S17, where the operating speed of the compressor 21 is reduced by a reduction amount corresponding to the increase amount of the discharge temperature, and the process proceeds to S18.

As excessive operating load on the compressor 21 is undesirable due to the risk of deterioration of durability or damage, the operating speed of the compressor 21 is reduced by a reduction amount corresponding to the increase in discharge temperature to keep the increase in discharge pressure small and reduce the operating load on the compressor 21. The reduction amount of the operating speed of the compressor 21 is set appropriately according to the compressor 21, for example, by reducing it by 5 rotations/second for every 0.5°C increase in discharge temperature. At this time, in order to further reduce the operating load on the compressor 21, the operating speed is gradually reduced, for example by reducing it by one rotation per second.

In S18, the refrigerant discharge temperature after the operating speed of the compressor 21 is reduced is obtained, and the process proceeds to S19. Then, in S19, it is determined whether the refrigerant discharge temperature has started to decrease. If the determination in S19 is No, the process returns to S17, and the operating speed of the compressor 21 is reduced until the refrigerant discharge temperature starts to decrease. Note that the operating speed may not be reduced below a preset lower limit operating speed.

On the other hand, if the determination in S19 is Yes, the process proceeds to S20, where the operating speed of the compressor 21 is increased by an increment corresponding to the decrease in the discharge temperature, and the process returns to S12. As the blockage is eliminated and the discharge pressure of the compressor 21 decreases, and the discharge temperature decreases, the operating speed of the compressor 21 is increased. In this case, in order to reduce the operating load on the compressor 21, the operating speed is increased by, for example, 5 rotations/second for every 0.5°C decrease in the discharge temperature, and in order to further reduce the operating load on the compressor 21, the operating speed is increased gradually, for example, by 1 rotation per second. Finally, the operating speed of the compressor 21 is returned to the operating speed at the start of the defrosting operation.

During long-term hot water storage operation, frost may form on the evaporative heat exchanger 24 several times, and defrosting operation may be performed each time. On the other hand, if the outside temperature is relatively high, frost does not form on the evaporative heat exchanger 24, and hot water storage is completed without performing defrosting operation.

The operation and effects of the above-mentioned hot water storage and supply device 1 will now be described.
The hot water storage and hot water supply device 1 stores hot water heated by the heat pump unit 4 in the hot water storage tank 2, and when frost formation on the evaporative heat exchanger 24 of the heat pump unit 4 is detected during the hot water storage operation, a defrosting operation is started to remove the frost. When an increase in the discharge temperature of the refrigerant discharged by the compressor 21 is detected during the defrosting operation after a predetermined time has elapsed since the start of the defrosting operation, the operating speed of the compressor 21 is reduced. The increase in the discharge temperature of the refrigerant discharged by the compressor 21 during the defrosting operation is caused by an increase in the discharge pressure of the compressor 21, and the operating load of the compressor 21 is increased. Therefore, the operating speed of the compressor 21 can be reduced to reduce the excessive operating load on the compressor 21 of the heat pump unit 4 during the defrosting operation, and the deterioration of durability or damage to the compressor 21 can be prevented.

At this time, the reduction range of the operating speed of the compressor 21 is set in accordance with the increase range of the discharge temperature of the compressor 21, so that the operating speed is reduced in response to an increase in the operating load of the compressor 21, thereby mitigating the increase in the operating load.

In addition, when a decrease in the discharge temperature of the compressor 21 is detected after the operating load of the compressor 21 is reduced, the increase range of the operating speed of the compressor 21 is set corresponding to the decrease range of the discharge temperature, and the operating speed of the compressor 21 is increased. The decrease in the discharge temperature of the refrigerant discharged from the compressor 21 after the operating speed is reduced is due to a decrease in the discharge pressure of the compressor 21, and since the operating load on the compressor 21 is reduced, the operating speed of the compressor 21 is increased to approach the state before the operating speed was reduced. Therefore, after the excessive operating load on the compressor 21 of the heat pump unit 4 during the defrosting operation is no longer imposed, the operating speed is brought closer to the operating speed at the start of the defrosting operation, so that the time required for the defrosting operation can be prevented from being long.

The reduction of the excessive operating load of the compressor 21 during the defrosting operation can be applied to equipment equipped with a heat pump unit 4. In addition, a person skilled in the art can implement the above embodiment in various modified forms without departing from the spirit of the present invention, and the present invention includes such modified forms.

1: Hot water storage and hot water supply device 2: Hot water storage tanks 2a to 2d: Hot water storage temperature sensor (hot water storage heat quantity detection means)
Description of the Reference Number 3: Hot water storage unit 4: Heat pump unit 5: Auxiliary heat source unit 6: Hot water tap 7: Hot water storage pump 8: Supply passage 9: Return passage 9a: Return branch passage 10: Switching valve 11: Water supply passage 11a: Water supply branch passage 11b: Water supply temperature sensor 12: Hot water outlet passage 12a: Hot water outlet flow rate sensor 12b: Hot water storage tank outlet hot water temperature sensor 12c: Hot water outlet temperature sensor 14: Mixing valve 15, 16: Hot water passage 18: Hot water storage unit control unit (control unit)
19: Operation terminal 21: Compressor
22: Condenser heat exchanger 23: Expansion valve 24: Evaporator heat exchanger 25: Refrigerant circuit
26: Discharge temperature sensor (discharge temperature detection means)
27: Evaporative heat exchange outlet temperature sensor (evaporative heat exchange outlet temperature detection means)
28: Blower fan 29: Heat pump unit control section

Claims (3)

A hot water storage and hot water supply device including a heat pump unit configured by connecting a compressor, a condensing heat exchanger, an expansion valve, and an evaporative heat exchanger by a refrigerant circuit, a hot water storage tank, and a control unit that controls a hot water storage operation in which hot water heated by the heat pump unit is stored in the hot water storage tank,
a discharge temperature detection means for detecting a discharge temperature of the refrigerant of the compressor, and an evaporation heat exchange outlet temperature detection means for detecting a refrigerant temperature at an outlet of the evaporation heat exchanger,
The control unit is characterized in that when frost is detected on the evaporative heat exchanger based on the refrigerant temperature at the outlet of the evaporative heat exchanger during the hot water storage operation, it starts a defrosting operation to remove the frost, and when an increase in the discharge temperature is detected during the defrosting operation after a predetermined time has elapsed since the start of the defrosting operation, it reduces the operating speed of the compressor. The hot water storage and hot water supply device according to claim 1, characterized in that the control unit sets the amount of decrease in the operating speed according to the amount of increase in the discharge temperature. The hot water storage and hot water supply device according to claim 1 or 2, characterized in that, when the control unit detects a decrease in the discharge temperature after reducing the operating speed, the control unit increases the operating speed by setting an increase in the operating speed according to the decrease in the discharge temperature.

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