JP2017207234A - Heat pump type hot water supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump type hot water supply system enabling improvement a COP of a heat storage operation.SOLUTION: A heat pump type hot water supply system includes: a heat pump device for heating water; a hot water storage tank; and control means for controlling a hot water delivery temperature that is a temperature of hot water flowing out from the heat pump device. When a heat storage operation that is an operation for storing the hot water heated by the heat pump device in the hot water storage tank is performed, the control means selects either of a first mode or a second mode in which arrival time from starting of the heat pump device until the hot water delivery temperature reaches a target hot water delivery temperature is longer than that in the first mode. The first mode or the second mode is selected in accordance with at least one of duration of the heat storage operation, a temperature of hot water in the hot water storage tank and an operation mode set by a user.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat pump hot water supply system.

  The heat pump type hot water heater disclosed in Patent Document 1 below is configured as follows. Heat pump unit control means for controlling the heating capacity of the heat pump unit is provided. The heat pump unit control means is configured such that the heating capacity of the heat pump unit in the night time zone is lower than the rated heating capacity that is the heating capacity in the operation mode at the rated output of the heat pump unit, and at least the liquid to be heated corresponding to the full capacity of the hot water storage unit. Is a heating capacity capable of boiling up to a predetermined tapping temperature during night hours.

JP 2013-167409 A

  In the initial stage of the heat storage operation, the temperature of hot water flowing out from the heat pump device may overshoot the target value, and the coefficient of performance (COP) may be lowered. The technique of Patent Document 1 cannot prevent such a decrease in COP.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a heat pump hot water supply system that can improve the COP of the heat storage operation.

  A heat pump hot water supply system according to the present invention includes a heat pump device that heats water, a hot water storage tank, and a control unit that controls a hot water temperature that is a temperature of hot water flowing out of the heat pump device, and the control unit includes the heat pump device. When performing a heat storage operation, which is an operation of accumulating hot water heated by the hot water storage tank, the first mode and the arrival time that is the time from the start of the heat pump device until the hot water temperature reaches the target hot water temperature Select one of the second mode, which is longer than the first mode, to at least one of the time to continue the heat storage operation, the temperature of the hot water in the hot water storage tank, and the operation mode set by the user In response, the first mode or the second mode is selected.

  According to the heat pump hot water supply system of the present invention, it is possible to improve the COP of the heat storage operation.

It is a figure which shows the heat pump type hot water supply system of Embodiment 1. FIG. It is a figure which shows the example of the temporal change of the tapping temperature at the time of the heat storage driving | operation in the 2nd mode in Embodiment 1. FIG. 6 is a diagram illustrating an example of temporal change in COP during the heat storage operation in the second mode in Embodiment 1. FIG. It is a figure which shows the example of the temporal change of the tapping temperature at the time of the heat storage driving | operation in the 1st mode in Embodiment 1. FIG. 6 is a diagram illustrating an example of a temporal change in COP during the heat storage operation in the first mode in Embodiment 1. FIG. It is a figure which shows the example of the temporal change of the tapping temperature at the time of the heat storage driving | operation in the 2nd mode in Embodiment 1. FIG.

  Hereinafter, embodiments will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals, and redundant description is simplified or omitted. The present disclosure may include any combination of configurations that can be combined among the configurations described in the following embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a heat pump hot water supply system 1 according to a first embodiment. As shown in FIG. 1, the heat pump hot water supply system 1 according to the first embodiment includes a heat pump device 2 that heats water and a hot water storage unit 24 that includes a hot water storage tank 8. In the present embodiment, the heat pump device 2 and the hot water storage unit 24 are separate bodies. Not limited to such a configuration, the heat pump device 2 and the hot water storage unit 24 may be integrally configured.

  The heat pump device 2 includes a refrigerant circuit in which devices including a compressor 3, a heat exchanger 4, an expansion valve 5, and an evaporator 6 are annularly connected by a refrigerant pipe 7. Water is heated by exchanging heat in the heat exchanger 4 between the high-temperature and high-pressure refrigerant compressed by the compressor 3 and the water. The expansion valve 5 expands the high-pressure refrigerant after heat exchange into a low-pressure refrigerant. The evaporator 6 evaporates the low-pressure refrigerant. The evaporator 6 may evaporate the low-pressure refrigerant with heat of any one of outside air, groundwater, drainage, and solar hot water, for example. The heat pump device 2 may use carbon dioxide, which is a natural refrigerant, as a refrigerant.

  In addition to the hot water storage tank 8, the hot water storage unit 24 includes devices such as a control device 9, a circulation pump 10, a mixing valve 14, a flow path switching valve 17, a relief valve 16, and a pressure reducing valve 18. Inside the hot water storage tank 8, a temperature stratification is formed in which the upper side has a high temperature and the lower side has a low temperature due to a difference in water density due to a temperature difference. In the hot water storage tank 8, hot water heated by the heat pump device 2 is stored on the upper side, and water before being heated is stored on the lower side.

  A water supply pipe 19 is connected to a water inlet 83 provided in the lower part of the hot water storage tank 8. The upstream side of the water supply pipe 19 is connected to a water source such as a water supply. The pressure reducing valve 18 connected in the middle of the water supply pipe 19 reduces the water pressure of the water source to a predetermined pressure. As water flows into the hot water storage tank 8 from the water supply pipe 19, the hot water storage tank 8 is maintained in a full state. A water supply temperature sensor 28 is attached to the water supply pipe 19. The water supply temperature sensor 28 detects the temperature of water supplied from a water source (hereinafter referred to as “water supply temperature”).

  The hot water storage tank 8 is provided with a plurality of tank temperature sensors 23 for detecting the temperature distribution of the hot water in the vertical direction. For example, assuming that the capacity of the hot water storage tank 8 is 370L, the tank temperature sensors 23 may be arranged at positions where the volume from the upper part of the hot water storage tank 8 is 50L, 100L, 150L, 200L, 250L, 300L. By detecting the temperature distribution of hot water in the vertical direction by these tank temperature sensors 23, the temperature and amount of hot water in the hot water storage tank 8 can be detected. The amount of heat stored in the hot water storage tank 8 can be calculated from the temperature and amount of hot water in the hot water storage tank 8.

  The mixing valve 14 includes an a port, a b port, and a c port. One end of the hot water supply pipe 13 communicates with an upper port 81 provided at the upper part of the hot water storage tank 8. The other end of the hot water supply pipe 13 is connected to the a port of the mixing valve 14. A water supply pipe 26 branches from a water supply pipe 19 downstream of the pressure reducing valve 18. The water supply pipe 26 is connected to the b port of the mixing valve 14. A hot water supply pipe 27 is connected to the c port of the mixing valve 14. The downstream side of the hot water supply pipe 27 is connected to the hot water supply terminal 15 outside the hot water storage unit 24. The hot water supply terminal 15 may include, for example, at least one of a shower, a kitchen sink faucet, a sink faucet, and a bathtub. A hot water supply temperature sensor 29 is attached to the hot water supply pipe 27. The hot water supply temperature sensor 29 detects the temperature of hot water flowing to the hot water supply terminal 15 (hereinafter referred to as “hot water supply temperature”). The hot water supply temperature can be adjusted by mixing hot water and water with the mixing valve 14.

  The water outlet 84 provided at the lower part of the hot water storage tank 8 is connected to the water inlet of the heat exchanger 4 of the heat pump device 2 via the conduit 11. A circulation pump 10 is connected in the middle of the conduit 11. The conduit 11 partially passes through the space outside the heat pump device 2 and the hot water storage unit 24.

  The flow path switching valve 17 includes an a port, a b port, and a c port. The flow path switching valve 17 can be switched between a first state in which the a port is communicated with the b port and the c port is blocked, and a second state in which the a port is communicated with the c port and the b port is blocked. The flow path switching valve 17 is an example of a flow path switching means.

  The water outlet of the heat exchanger 4 of the heat pump device 2 is connected to the a port of the flow path switching valve 17 via the conduit 12. The conduit 12 partially passes through the space outside the heat pump device 2 and the hot water storage unit 24. A tapping temperature sensor 21 is attached to the conduit 12. The hot water temperature sensor 21 detects the temperature of hot water flowing out from the heat exchanger 4 of the heat pump device 2 (hereinafter referred to as “hot water temperature”). The circulation pump 10 may be connected in the middle of the conduit 12 instead of the illustrated position.

  The b port of the flow path switching valve 17 communicates with the upper port 81 of the hot water storage tank 8 through the upper conduit 25. The c port of the flow path switching valve 17 is connected via a bypass conduit 20 to a water return port 82 provided at the lower part of the hot water storage tank 8. In the illustrated configuration, the upper conduit 25 and the hot water supply pipe 13 communicate with the common upper port 81, but instead of such a configuration, the upper conduit 25 and the hot water supply pipe 13 are separately provided in the upper part of the hot water storage tank 8. May be connected.

  The control device 9 is an example of a control unit that controls the operation of the heat pump hot water supply system 1. Each actuator and each sensor included in the heat pump hot water supply system 1 are electrically connected to the control device 9. That is, the heat pump device 2, the circulation pump 10, the mixing valve 14, the flow path switching valve 17, the hot water temperature sensor 21, the tank temperature sensor 23, the hot water temperature sensor 28, the hot water temperature sensor 29, etc. are electrically connected to the control device 9. Connected to.

  The operation terminal 22 is connected to the control device 9 so as to be able to perform data communication in both directions wirelessly or by wire. The operation terminal 22 is an example of a user interface. The operation terminal 22 may be installed in a kitchen or a bathroom, for example. The operation terminal 22 may include an operation unit operated by a user and a display unit that displays information related to the heat pump hot water supply system 1. The user can input commands relating to the operation of the heat pump hot water supply system 1 and changes in set values to the operation terminal 22. The operation terminal 22 transmits the input information to the control device 9. The control device 9 may control the operation of the heat pump hot water supply system 1 according to the information received from the operation terminal 22.

  Although not shown in the figure, the hot water storage unit 24 may be further provided with a device used for filling a bath, a pipe for reheating the bath, a heat exchanger, a valve, a sensor, and the like.

  The heat pump hot water supply system 1 can execute a heat storage operation. The heat storage operation is an operation in which hot water heated by the heat pump device 2 is accumulated in the hot water storage tank 8. At the time of heat storage operation, it is as follows. The heat pump device 2 and the circulation pump 10 are operated. The flow path switching valve 17 is set to the first state. Water flowing out from the water outlet 84 at the lower part of the hot water storage tank 8 is led to the heat exchanger 4 of the heat pump device 2 through the conduit 11, the circulation pump 10, and the conduit 11. Hot water heated in the heat exchanger 4 flows into the hot water storage tank 8 from the upper port 81 through the conduit 12, the flow path switching valve 17, and the upper conduit 25. In the hot water storage tank 8, hot water accumulates from top to bottom.

  During the heat storage operation, the control device 9 can control the hot water temperature detected by the hot water temperature sensor 21 to be equal to the target hot water temperature by controlling one or both of the heat pump device 2 and the circulation pump 10. . In that case, it may be as follows. The control device 9 may control the flow rate of water by adjusting the rotational speed of the circulation pump 10. The control device 9 may control the refrigerant discharge temperature from the compressor 3 by adjusting at least one of the opening degree of the expansion valve 5 and the driving speed of the compressor 3. Based on the deviation between the target hot water temperature and the hot water temperature detected by the hot water temperature sensor 21, the control device 9 includes the rotational speed of the circulation pump 10, the driving speed of the compressor 3, and the opening of the expansion valve 5. At least one of these may be proportional control, integral control, differential control, or a combination of two or more thereof.

  When the water in the hot water storage tank 8 is heated by the heat storage operation to generate expanded water and gasified dissolved air, the internal pressure of the hot water storage tank 8 increases. When the internal pressure of the hot water storage tank 8 rises, the relief valve 16 connected to the upper part of the hot water storage tank 8 opens and the expanded water and gasified dissolved air are released outside the system, so that the internal pressure of the hot water storage tank 8 is excessively increased. Is prevented.

  The heat pump hot water supply system 1 can execute a bypass operation. During bypass operation: The circulation pump 10 is operated. The flow path switching valve 17 is set to the second state. Water flowing out from the water outlet 84 at the lower part of the hot water storage tank 8 is led to the heat exchanger 4 of the heat pump device 2 through the conduit 11, the circulation pump 10, and the conduit 11. The water that has passed through the heat exchanger 4 flows into the hot water storage tank 8 from the water return port 82 through the conduit 12, the flow path switching valve 17, and the bypass conduit 20.

  The control device 9 may perform the bypass operation at the initial stage of the heat storage operation, that is, immediately after the heat pump device 2 is activated. Immediately after the heat pump device 2 is activated, water cannot be heated sufficiently, so that the hot water temperature is less than the target hot water temperature. The control device 9 may shift to the heat storage operation while waiting for the hot water temperature to rise while performing the bypass operation. For example, after the heat pump device 2 is started, the hot water temperature detected by the hot water temperature sensor 21 may wait for the hot water temperature to reach a predetermined threshold value, and the operation may be shifted from the bypass operation to the heat storage operation. The control device 9 can shift from the bypass operation to the heat storage operation by switching the flow path switching valve 17 from the second state to the first state. By doing as mentioned above, low temperature water can be prevented from flowing into the upper part of the hot water storage tank 8. The control device 9 may perform a bypass operation for other purposes, for example, for preventing the conduits 11 and 12 from freezing.

  Next, the hot water supply operation by the heat pump hot water supply system 1 will be described. When the hot water supply terminal 15 is opened, the hot water supply operation starts. During hot water supply operation, the operation is as follows. Hot water flowing out from the upper part of the hot water storage tank 8 flows into the a port of the mixing valve 14 through the hot water supply pipe 13. Water flows into the b port of the mixing valve 14 through the water supply pipe 26. The hot water and water are mixed by the mixing valve 14. The mixing valve 14 can change the mixing ratio of hot water and water. The mixed hot water is supplied to the hot water supply terminal 15 through the hot water supply pipe 27. During the hot water supply operation, the control device 9 may control the operation of the mixing valve 14 so that the hot water supply temperature detected by the hot water supply temperature sensor 29 becomes equal to the target value. The target value of the hot water supply temperature may be a temperature set by the user on the operation terminal 22. In the following description, the target value of the hot water supply temperature is referred to as “hot water supply set temperature”.

  In starting the heat storage operation, the control device 9 calculates a necessary heat storage operation time. The heat storage operation time is a time for which the heat storage operation is continued. The control device 9 determines the necessary heat storage amount based on the actual value of the amount of hot water used or the amount of heat used for a plurality of days in the past (for example, the past two weeks) and the current hot water storage amount or heat storage amount detected by the tank temperature sensor 23. The operation time may be calculated.

  As described above, immediately after the heat pump device 2 is activated, the water cannot be sufficiently heated, so that the hot water temperature does not reach the target hot water temperature. In the following description, the time from when the heat pump device 2 is started until the hot water temperature reaches the target hot water temperature is referred to as “arrival time”. When the heat storage operation is performed, the control device 9 selects either the first mode or the second mode. The second mode is a mode in which the arrival time is longer than that of the first mode.

  When the first mode is selected, there is an advantage that the arrival time is shorter than that in the second mode. Further, when the first mode is selected, there is an advantage that the amount of hot water having a temperature lower than the target hot water temperature flows into the hot water storage tank 8 is smaller than that in the second mode.

  On the other hand, the second mode has the following advantages. When the hot water temperature is raised to the target hot water temperature in a short time after the heat pump device 2 is activated, the hot water temperature tends to overshoot the target hot water temperature. When the hot water temperature overshoots the target hot water temperature, the COP decreases. Compared to the first mode, the second mode takes a longer time to raise the hot water temperature to the target hot water temperature. For this reason, in the second mode, the hot water temperature is less likely to overshoot the target hot water temperature as compared to the first mode. Therefore, the COP is less likely to decrease in the second mode than in the first mode. Therefore, when the second mode is selected, there is an advantage that the COP of the heat storage operation can be improved as compared with the first mode.

  In the present embodiment, the first mode is as follows. The control device 9 controls one or both of the heat pump device 2 and the circulation pump 10 so that the hot water temperature becomes equal to the target hot water temperature from the start of the heat pump device 2. As a result, after the heat pump device 2 is started, the hot water temperature continuously rises to the target hot water temperature.

  In the present embodiment, the second mode is as follows. After the heat pump device 2 is activated, the control device 9 first controls one or both of the heat pump device 2 and the circulation pump 10 so that the tapping temperature becomes equal to the intermediate target temperature. The intermediate target temperature is a temperature lower than the target hot water temperature. The control device 9 continues the operation for making the tapping temperature equal to the intermediate target temperature for a predetermined time. Thereafter, the control device 9 controls either one or both of the heat pump device 2 and the circulation pump 10 so that the hot water temperature becomes equal to the target hot water temperature. In such a second mode, the tapping temperature rises stepwise up to the target tapping temperature. According to the present embodiment, in the second mode, by raising the hot water temperature stepwise, the occurrence of hot water temperature overshoot can be more reliably prevented, and the COP can be further improved.

  In the present embodiment, an example in which the hot water temperature rises in two stages in the second mode will be described. That is, in the present embodiment, it is as follows. In the second mode, the control device 9 divides the heat storage operation into a first stage and a second stage. In the first stage, the control device 9 controls one or both of the heat pump device 2 and the circulation pump 10 so that the tapping temperature becomes equal to the intermediate target temperature. In the second stage, the control device 9 controls either one or both of the heat pump device 2 and the circulation pump 10 so that the hot water temperature becomes equal to the target hot water temperature.

  Not only in this example, but in the second mode, the tapping temperature may be controlled to increase in three or more stages. In that case, a plurality of different intermediate target temperatures may be set, and the intermediate target temperature may be increased stepwise. In the present invention, the tapping temperature may be controlled to rise continuously during the second mode. In that case, either or both of the heat pump device 2 and the circulation pump 10 are set so that the rising speed of the tapping temperature during the second mode is slower than the rising speed of the tapping temperature during the first mode. Can be controlled.

  If it is this Embodiment, COP of heat storage driving | operation can be improved because the 2nd mode can be selected. As will be described below, in the present embodiment, the control device 9 responds to at least one of the heat storage operation time, the temperature of the hot water in the hot water storage tank 8, and the operation mode set by the user. To select the first mode or the second mode. Thereby, the first mode or the second mode can be appropriately selected.

  The control device 9 may select either the first mode or the second mode according to the heat storage operation time. When the heat storage operation time is long, there is no problem even if the arrival time is long. On the other hand, when the heat storage operation time is short, if the arrival time is long, the hot water temperature does not reach the target hot water temperature by the end of the heat storage operation, or the temperature of the hot water in the hot water storage tank 8 after the heat storage operation is high. There is a possibility of a significant decrease compared to before the heat storage operation. For this reason, the control device 9 selects the second mode when the necessary heat storage operation time calculated before the start of the heat storage operation is longer than the reference, and selects the first mode otherwise. May be.

The relationship of the following formula (I) is established between the heating capacity of the heat pump device 2, the flow rate of water, and the water temperature.
Q = ρ · Cp · (x / 60) · (Tp−T0) (I)
Q [kW]: Heating capacity ρ [kg / L]: Water density (constant)
Cp [kJ / kg · ° C]: constant-pressure specific heat of water (constant)
x [L / min]: Flow rate of water T0 [° C]: Feed water temperature Tp [° C]: Hot water temperature

  As an example, there is 9 ° C. water in the entire hot water storage tank 8 with a capacity of 370 L, the heating capacity of the heat pump device 2 is 4.5 kW, the intermediate target temperature of the first stage is 50 ° C., the operation time of the first stage is 20 minutes, Assuming that the target temperature of the second stage is 70 ° C. and the operation time of the second stage is ti2 [minutes], the flow rate of the water in the first stage and the second stage is 1.57 L / each from the above formula (I). Min, 1.06 L / min. In the following description, the volume of hot water flowing out from the heat pump device 2, that is, the volume of hot water accumulated in the hot water storage tank 8 is referred to as “accumulated hot water amount”. The amount of accumulated hot water is obtained by multiplying the flow rate of water by the operation time. In the above example, the amount of accumulated hot water in the first stage is obtained as 31L, and the amount of accumulated hot water in the second stage is obtained as (1.06 · ti2) L.

The amount of heat stored in the hot water storage tank 8 is represented by the following relational expression (II).
Heat storage amount of hot water storage tank 8 = ρ · Cp · V · (T−T0) (II)
V [L]: Volume of hot water in the hot water storage tank 8 T [° C.]: Temperature of hot water in the hot water storage tank 8

In formula (II), the amount of heat stored before the heat storage operation is added to the amount of heat stored after the heat storage operation and the amount of heat stored after the heat storage operation is added. Will be equal. That is, the relationship of the following formula (III) is established.
ρ · Cp · V0 · (Tb−T0) + ρ · Cp · V1 · (Tp1−T0) + ρ · Cp · V2 · (Tp2−T0) = ρ · Cp · (V0 + V1 + V2) · (Ta−T0) (III) )
V0 [L]: Volume of hot water in the hot water storage tank 8 before the heat storage operation V1 [L]: Accumulated hot water amount in the first stage V2 [L]: Accumulated hot water amount in the second stage Tb [° C]: Before the heat storage operation Temperature of hot water in the hot water storage tank 8 Ta [° C.]: Temperature of hot water in the hot water storage tank 8 after the heat storage operation Tp 1 [° C.]: Intermediate target temperature of the first stage Tp 2 [° C.]: Target hot water temperature of the second stage

  The control device 9 may select either the first mode or the second mode according to the temperature of the hot water in the hot water storage tank 8. When the second mode is selected, the temperature of the hot water in the hot water storage tank 8 after the heat storage operation becomes lower than when the first mode is selected. Further, when the heat storage operation is performed in the second mode, the temperature of the hot water in the hot water storage tank 8 after the heat storage operation may be lower than the temperature of the hot water in the hot water storage tank 8 before the heat storage operation. When the temperature of the hot water in the hot water storage tank 8 is low, it may be better to select the first mode for the above reason. On the other hand, when the temperature of the hot water in the hot water storage tank 8 is high, there is no problem even if the second mode is selected. For this reason, the control device 9 may select the second mode when the temperature of the hot water in the hot water storage tank 8 is higher than the reference, and may select the first mode otherwise. .

  The control device 9 may determine the reference for selecting the first mode or the second mode as follows. When it is assumed that the second mode is selected, the control device 9 selects the second mode when the temperature of the hot water in the hot water storage tank 8 after the heat storage operation is predicted to be higher than the maximum value of the hot water supply set temperature. Otherwise, the first mode may be selected. As an example, the maximum value of the hot water supply set temperature is 60 ° C. From the above-mentioned numerical values and the formula (III), the second stage operation time ti2 such that the temperature of the hot water in the hot water storage tank 8 after the heat storage operation is 60 ° C. is obtained as 29.2 minutes. If the operation is performed for 49.2 minutes or more, which is 20 minutes as the first stage operation time, the temperature of the hot water in the hot water storage tank 8 after the heat storage operation when the second mode is selected becomes 60 ° C. or more. . Therefore, the control device 9 may select the second mode when the heat storage operation time is 49.2 minutes or more, and may select the first mode otherwise.

  Further, when the necessary heat storage operation time is, for example, 60 minutes, the following may be performed. As an example, there is 100 L of 80 ° C. hot water in a hot water storage tank 8 with a capacity of 370 L, the heating capacity of the heat pump device 2 is 4.5 kW, the feed water temperature is 9 ° C., the intermediate target temperature of the first stage is 50 ° C., the first stage Assuming that the operation time is 20 minutes, the target hot water temperature of the second stage is 70 ° C., and the operation time of the second stage is 40 minutes, the flow rate of the water in the first stage and the second stage is They are determined as 1.57 L / min and 1.06 L / min, respectively. Further, the amount of accumulated hot water in the first stage is obtained as 31L, and the amount of accumulated hot water in the second stage is obtained as 42L. The temperature of the hot water in the hot water storage tank 8 after the heat storage operation is obtained as 72 ° C. from each numerical value and the formula (III). In this example, since hot water of 60 ° C. or higher, which is the maximum value of the hot water supply set temperature, can be stored, the control device 9 performs the heat storage operation in the second mode.

  FIG. 2 is a diagram illustrating an example of temporal change in the temperature of the hot water during the heat storage operation in the second mode in the first embodiment. In this example, it is as follows. The hot water temperature reaches the first intermediate target temperature Tp1 at time tp after the heat pump device 2 is started. Thereafter, until the predetermined time tc, the state in which the tapping temperature is equal to the intermediate target temperature Tp1 is maintained. Shift to the second stage from time tc. The tapping temperature reaches the target tapping temperature Tp at the second time t2.

  FIG. 3 is a diagram illustrating an example of a temporal change in COP during the heat storage operation in the second mode in the first embodiment. In this example, it is as follows. The COP reaches the peak value Ct at time tp after the heat pump device 2 is started. Thereafter, until the predetermined time tc, the COP maintains a state equal to the peak value Ct. At the beginning of the second stage from time tc, the COP decreases. At the second time t2, COP becomes equal to Cstd. Thereafter, the COP remains equal to Cstd. Cstd corresponds to steady COP. In general, the lower the tapping temperature, the higher the COP. For this reason, as shown in FIG. 3, the first stage COP is higher than the second stage COP.

  FIG. 4 is a diagram illustrating an example of a temporal change in the temperature of the hot water during the heat storage operation in the first mode in the first embodiment. In this example, it is as follows. The hot water temperature continuously rises to the target hot water temperature Tp after the heat pump device 2 is started. When the target hot water temperature Tp is high, the follow-up of the water flow rate control is delayed when the refrigerant discharge temperature rises, so that the hot water temperature overshoot as seen at time tb is likely to occur. Thereafter, the hot water temperature reaches the target hot water temperature Tp and stabilizes at the first time t1.

  FIG. 5 is a diagram illustrating an example of a temporal change in COP during the heat storage operation in the first mode in the first embodiment. In this example, it is as follows. The COP reaches Cstd of the steady COP at the first time t1 after the heat pump device 2 is started, but the COP is lowered by the occurrence of overshoot as seen at the time tb in FIG. Further, when the deviation between the target hot water temperature and the actual hot water temperature becomes large at the initial stage of the heat storage operation, the COP is lowered by performing control to greatly reduce the water flow rate.

  The heat pump hot water supply system 1 according to the present embodiment may include a unit that allows a user to set an operation mode that prioritizes energy saving. The name of the operation mode giving priority to energy saving may be any name, for example, an energy saving mode, a power saving mode, or the like. The user may be able to set an operation mode that prioritizes energy saving by operating the operation terminal 22. The control device 9 may select the second mode when the operation mode giving priority to energy saving is set. When the operation mode giving priority to energy saving is set, the control device 9 may increase the opportunities for selecting the second mode by relaxing the criteria for selecting the second mode. Alternatively, when the operation mode giving priority to energy saving is set, the control device 9 may always select the second mode regardless of the heat storage operation time and the temperature of the hot water in the hot water storage tank 8. By doing as described above, it is possible to more reliably increase the chances of selecting the second mode with a high COP in accordance with the intention of the user who has set the operation mode giving priority to energy saving.

  FIG. 6 is a diagram showing an example of a temporal change in the temperature of the hot water during the heat storage operation in the second mode in the first embodiment. The tapping temperature shown by the solid line in FIG. 6 is an example in the case of the target tapping temperature Tp. The tapping temperature shown by the broken line in FIG. 6 is an example in the case of the target tapping temperature Tp ′ higher than the target tapping temperature Tp. In the present embodiment, the tapping temperature in the second stage increases at a substantially constant rate until the target tapping temperature is reached. For this reason, the arrival time t2 'in the case of the target hot water temperature Tp' is longer than the arrival time t2 in the case of the target hot water temperature Tp. Thus, in this Embodiment, the arrival time in 2nd mode is lengthened, so that target hot-water temperature is high. By doing in this way, generation | occurrence | production of the overshoot of tapping temperature can be prevented more reliably, and COP can further be improved.

Embodiment 2. FIG.
Next, the second embodiment will be described. The difference from the first embodiment will be mainly described, and the description of the same or corresponding parts will be simplified or omitted. Since the hardware configuration of the heat pump hot water supply system 1 of the second embodiment is the same as that of the first embodiment, the drawings and description are omitted.

  In Embodiment 1, the operation time of the first stage in the second mode is set to a certain time. Instead of such a control method, the control device 9 may calculate the operation time of the first stage of the second mode from the required amount of heat as in the second embodiment. Hereinafter, processing performed by the control device 9 in the second embodiment will be described based on specific numerical examples.

  It is assumed that the necessary heat storage operation time calculated by the control device 9 is 180 minutes. In this case, even if hot water having a temperature lower than the target hot water temperature flows into the hot water storage tank 8 by the heat storage operation in the second mode, the temperature of the hot water in the hot water storage tank 8 after the heat storage operation becomes equal to or higher than the hot water supply set temperature. Determine the operating time of the first stage.

The increase in the amount of heat storage due to the heat storage operation is expressed by the following formula (IV).
Increase in heat storage amount = Q · (60 · ti) ... (IV)
ti [min]: Thermal storage operation time

Since the amount of heat stored before the heat storage operation plus the amount of heat storage increased by the heat storage operation is equal to the amount of heat stored after the heat storage operation, the relationship of the following equation (V) is obtained from the equations (II) and (IV): Holds.
ρ · Cp · V0 · (Tb−T0) + Q · (60 · ti) = ρ · Cp · Vp · (Tp−T0) (V)
Vp [L]: Volume of hot water in the hot water storage tank 8 after the heat storage operation

  When there is 50 L of 68 ° C. hot water in the hot water storage tank 8 with a capacity of 370 L before the heat storage operation, the heating capacity of the heat pump device 2 is 4.5 kW, the heat storage operation time is 180 minutes, and the target hot water temperature is 60 ° C. From the numerical value and the equation (V), the volume of hot water in the hot water storage tank 8 after the heat storage operation is obtained as 286L. In this case, since the volume 286L of hot water in the hot water storage tank 8 after the heat storage operation is within the capacity 370L of the hot water storage tank 8, it can be confirmed that the second mode heat storage operation can be performed.

Next, the first stage operation time ti1 [min] and the second stage operation time ti2 [min] are obtained. The amount of heat storage increased by the heat storage operation is expressed by the following formula (VI) from the formulas (II) and (IV).
ρ · Cp · V1 · (Tp1−T0) + ρ · Cp · V2 · (Tp2−T0) = Q · (60 · ti) (VI)

The amount of accumulated hot water V1 in the first stage and the amount of accumulated hot water V2 in the second stage are expressed by the following equations (VII) and (VIII).
V1 = x1 · ti1 (VII)
V2 = x2 · ti2 (VIII)
x1 [L / min]: Flow rate of water in the first stage x2 [L / min]: Flow rate of water in the second stage

The sum of the first stage operation time ti1 and the second stage operation time ti2 is equal to the heat storage operation time ti. That is, the following formula (IX) is established.
ti = ti1 + ti2 (IX)

  Assuming that the feed water temperature is 9 ° C., the intermediate target temperature of the first stage is 50 ° C., and the target hot water temperature of the second stage is 70 ° C., the flow rate of the water in the first stage and the second stage is It is determined as 1.57 L / min and 1.06 L / min. From the formulas (VI) to (IX), the first stage operating time ti1 is determined to be 99 minutes, and the second stage operating time ti2 is determined to be 81 minutes.

  According to this embodiment, when performing the heat storage operation in the second mode, the temperature of the hot water in the hot water storage tank 8 after the heat storage operation can be controlled so as to be more surely equal to or higher than the hot water supply set temperature.

  Each of the control device 9 and the control device included in the operation terminal 22 of the heat pump hot water supply system 1 may be configured as follows. Each function of the control device may be realized by a processing circuit. The processing circuit of the control device may comprise at least one processor and at least one memory. When the processing circuit includes at least one processor and at least one memory, each function of the control device may be realized by software, firmware, or a combination of software and firmware. At least one of the software and the firmware may be described as a program. At least one of the software and firmware may be stored in at least one memory. The at least one processor may realize each function of the control device by reading and executing a program stored in at least one memory. The at least one memory may include a nonvolatile or volatile semiconductor memory, a magnetic disk, or the like.

  The processing circuit of the control device may include at least one dedicated hardware. When the processing circuit includes at least one dedicated hardware, the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-). (Programmable Gate Array) or a combination thereof. The function of each part of the control device may be realized by a processing circuit. Further, the functions of the respective units of the control device may be collectively realized by a processing circuit. Some of the functions of the control device may be realized by dedicated hardware, and the other part may be realized by software or firmware. The processing circuit may realize each function of the control device by hardware, software, firmware, or a combination thereof.

  The configuration is not limited to the configuration in which the operation is controlled by a single control device, and the configuration may be such that the operation is controlled by cooperation of a plurality of control devices.

DESCRIPTION OF SYMBOLS 1 Heat pump type hot water supply system, 2 Heat pump apparatus, 3 Compressor, 4 Heat exchanger, 5 Expansion valve, 6 Evaporator, 7 Refrigerant piping, 8 Hot water storage tank, 9 Control apparatus, 10 Circulation pump, 11,12 Conduit, 13 Hot water supply Pipe, 14 mixing valve, 15 hot water supply terminal, 16 relief valve, 17 flow path switching valve, 18 pressure reducing valve, 19 water supply pipe, 20 bypass conduit, 21 hot water temperature sensor, 22 operation terminal, 23 tank temperature sensor, 24 hot water storage unit, 25 upper pipe, 26 water supply pipe, 27 hot water supply pipe, 28 water supply temperature sensor, 29 hot water supply temperature sensor, 81 upper port, 82 water return port, 83 water inlet port, 84 water outlet port

Claims (7)

A heat pump device for heating water;
A hot water storage tank,
Control means for controlling the hot water temperature, which is the temperature of hot water flowing out of the heat pump device;
With
When the control means performs a heat storage operation, which is an operation of accumulating hot water heated by the heat pump device in the hot water storage tank, the hot water temperature is a target hot water temperature after the first mode and the heat pump device is started. Select one of the second mode, which is the time to reach the time is longer than the first mode,
The first mode or the second mode is selected according to at least one of the time for continuing the heat storage operation, the temperature of the hot water in the hot water storage tank, and the operation mode set by the user. Heat pump hot water supply system. The first mode is a mode in which the tapping temperature rises continuously,
2. The heat pump hot water supply system according to claim 1, wherein the second mode is a mode in which the hot water temperature rises stepwise.   The heat pump hot water supply system according to claim 1 or 2, wherein the second mode is selected when the time for which the heat storage operation is continued is longer than a reference.   The heat pump hot water supply system according to any one of claims 1 to 3, wherein the second mode is selected when the temperature of hot water in the hot water storage tank is higher than a reference. A means that allows the user to set the operation mode that prioritizes energy conservation,
The heat pump hot water supply system according to any one of claims 1 to 4, wherein the second mode is selected when an operation mode that prioritizes the energy saving is set.   When the second mode is selected, the control means controls the heat storage operation so that the temperature of the hot water in the hot water storage tank after the heat storage operation is equal to or higher than a hot water supply set temperature. The heat pump type hot water supply system according to any one of claims 5 to 6.   The heat pump hot water supply system according to any one of claims 1 to 6, wherein the arrival time in the second mode is increased as the target hot water temperature is higher.

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