JP6167299B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump water heater.

  Conventionally, there is a heat pump water heater of this type as shown in FIG. 16 (see, for example, Patent Document 1).

  FIG. 16 shows a conventional heat pump water heater described in Patent Document 1. As shown in FIG.

  As shown in FIG. 16, a compressor 104, a water-refrigerant heat exchanger 105, a decompression means 106, and an air heat exchanger (evaporator) 107 are connected in a tubular shape with a refrigerant pipe to form a heat pump cycle.

  Further, the bottom of the hot water storage tank 103, the pump 119, and the water refrigerant heat exchanger 105 are sequentially connected by an HP pipe 118. The outlet hot water temperature of the water-refrigerant heat exchanger 105 (hereinafter referred to as “hot water temperature”) is detected by a hot water temperature sensor 121 installed in the middle of the HP pipe 118.

  In the hot water storage operation mode, water at the bottom of the hot water storage tank 103 is transferred to the water / refrigerant heat exchanger 105 by the pump 119, where it is heated to become hot water by heat exchange with the refrigerant in the heat pump cycle, and the HP pipe 118, hot water supply It returns to the upper part of the hot water storage tank 103 via the pipe 120.

  At this time, the hot water temperature, the rotation speed of the pump 119, and the operation control of each component of the heat pump cycle are performed by the control device 125.

  A hot water discharge pipe 120 is connected to the top of the hot water storage tank 103, and a water supply pipe 109 is connected to the bottom of the hot water storage tank 103. The water supply pipe 109 is provided with a pressure reducing valve 110.

  The hot water mixing valve 111 mixes the hot water in the upper part of the hot water storage tank supplied from the hot water discharge pipe 120 and the water supplied from the water supply pipe 109 into hot water of a predetermined temperature, and supplies hot water from the hot water supply terminal 114 via the hot water supply pipe 113. Let The hot water temperature at the outlet of the hot water supply mixing valve 111 is detected by a hot water supply temperature sensor 122 installed in the middle of the hot water supply pipe 113.

  The hot water mixing valve 112 mixes the hot water in the upper part of the hot water storage tank supplied from the hot water pipe 120 and the water supplied from the water supply pipe 109 to supply hot water at a predetermined temperature to the hot water pipe 115 and the hot water on / off valve 116. Hot water is supplied to the bathtub 117 via

  The hot water temperature at the outlet of the hot water mixing valve 112 is detected by a hot water temperature sensor 123 installed in the middle of the hot water pipe 115. Further, the water level of the bathtub 117 is detected by a hot water pressure sensor 129 installed in the hot water pipe 115.

  In addition, the hot water operation to the bathtub 117 has a hot water operation mode, and at the start of the hot water operation mode, the heat pump cycle is started, the hot water on / off valve 116 is opened, and the HP pipe 118 is connected. The hot water passed through and the hot water from the hot water storage tank 103 merge at the connecting portion between the hot water pipe 120 and the HP pipe 118, and are supplied to the bathtub 117 through the hot water mixing valve 112 and the hot water pipe 115. .

  Moreover, the coefficient of performance of the heat pump cycle (hereinafter referred to as COP) is reduced by setting the temperature of the hot water in the hot water operation mode lower than that in the hot water operation mode and lowering the heating capacity. Efficient hot water operation is performed so as to be higher than the COP at the time. Furthermore, the heating capacity in the hot water operation mode is increased as the temperature of the hot water stored in the hot water storage tank (hot water storage temperature) is higher, so that efficient hot water operation can be performed.

JP 2012-154516 A

  However, in the conventional configuration, the heating capacity of the heat pump cycle in the hot water operation mode is increased as the hot water storage temperature is higher. Generally, when the outside air temperature is high, the hot water storage temperature is low, and the hot water storage amount is also set small. Therefore, in the conventional configuration, when the hot water operation mode is executed when the outside air temperature is high and the hot water storage temperature is low and the hot water is poured into the bathtub, the heating capacity of the heat pump cycle in the hot water operation mode is reduced, so The amount of stored hot water used will increase. In addition, since the amount of stored hot water is set to be small when the outside air temperature is high, there is a problem that the amount of remaining hot water decreases, and in some cases, hot water runs out.

  This invention solves the said conventional subject, and it aims at providing the heat pump water heater excellent in energy saving property, reducing the risk that hot water runs out.

In order to solve the above-described conventional problems, a heat pump water heater of the present invention includes a heat pump cycle in which a compressor, a water-refrigerant heat exchanger, a decompression unit, and an evaporator are connected by refrigerant piping, and hot water generated by heating with the heat pump cycle. A hot water storage tank for storing hot water, a pipe for returning hot water generated by heating in the heat pump cycle to the upper part of the hot water storage tank, a first hot water discharge pipe for extracting hot water from the upper part of the hot water storage tank, and at least a plurality of operation modes. Control means, and the plurality of operation modes include a hot water storage operation mode in which hot water generated by the heat pump cycle is stored in the hot water storage tank, and hot water having a temperature lower than that of the hot water storage operation mode is heated by the heat pump cycle. The hot water generated by the heat pump cycle is used for pouring into the bathtub. Includes a hot beam operation mode, the coefficient of performance of heat pump cycle in the hot beam operation mode, the higher than the coefficient of performance of the heat pump cycle in the hot water storage operation mode, and wherein, in the melt-beam operation mode, The heating capacity in the heat pump cycle is reduced when the hot water storage temperature of the hot water stored in the hot water storage tank is higher than when the hot water storage temperature is low.

  As a result, in the hot water operation mode, when the amount of heat held in the hot water storage tank is low, the heating capacity of the heat pump cycle increases, so the amount of hot water used in the hot water storage tank in the hot water operation mode decreases.

  ADVANTAGE OF THE INVENTION According to this invention, since the usage-amount of the hot water in the hot water storage tank in a hot water operation mode reduces, the heat pump water heater excellent in energy saving can be provided, reducing the risk that a hot water runout will occur.

1 is a schematic configuration diagram of a heat pump water heater in Embodiment 1 of the present invention. A graph showing changes in temperature distribution inside the hot water storage tank of the heat pump water heater Control flow chart at the start of hot water operation mode of the heat pump water heater The figure which shows the sequence of the operation | movement operation | movement of the hot water operation mode of the heat pump water heater The graph which shows the relationship between the tapping temperature of the heat pump water heater and the COP of the heat pump cycle The graph which shows the relationship between the heating capacity of a heat pump cycle and the compression ratio in the hot water operation mode of the heat pump water heater The graph which shows the relationship between the heating capability of the heat pump cycle in the hot water beam operation mode of the heat pump water heater, and the COP of the heat pump cycle The graph which shows the relationship between the heating capability of the heat pump cycle in the hot water operation mode of the heat pump water heater, and the bath pouring COP The figure which shows the relationship between the compressor rotation speed and bath pouring COP in the hot water operation mode of the same heat pump water heater. (A) A graph showing the relationship between the hot water storage temperature and the heating capacity when the hot water storage temperature is set to be smaller as the hot water storage temperature is higher in the hot water operation mode, and (b) the higher the hot water storage temperature is, the higher the hot water storage temperature is. Graph showing the relationship between hot water storage temperature and heating capacity when the capacity is set to be large The figure which shows the relationship between the hot water storage temperature before pouring into a bathtub and the amount of remaining hot water in the hot water storage operation mode of a heat pump water heater. (A) A graph showing the amount of remaining hot water after being poured into the bathtub when the heating capacity is set to be smaller as the hot water storage temperature is higher in the hot water operation mode, (b) the hot water storage temperature is higher in the hot water operation mode A graph showing the amount of remaining hot water after being poured into the bathtub when the heating capacity is set to be larger Control flow chart at the time of stop of hot water operation mode in the heat pump water heater of Embodiment 1 of the present invention (A) The figure which showed the change of the temperature distribution in a hot water storage tank when there is an intermediate temperature hot-water supply circuit in a heat pump water heater, (b) The change of the temperature distribution in the hot water storage tank when there is no intermediate temperature hot-water supply circuit in a heat pump water heater Illustration shown The schematic block diagram of the heat pump water heater in Embodiment 2 of this invention. Configuration diagram of conventional heat pump water heater

A first invention is a heat pump cycle in which a compressor, a water refrigerant heat exchanger, a decompression means, and an evaporator are connected by refrigerant piping, a hot water storage tank for storing hot water heated and generated by the heat pump cycle, and heating by the heat pump cycle A pipe for returning the generated hot water to the upper part of the hot water storage tank, a first hot water discharge pipe for taking out hot water from the upper part of the hot water storage tank, and a control means for executing at least a plurality of operation modes. Is a hot water storage operation mode in which hot water generated by the heat pump cycle is stored in the hot water storage tank, hot water having a temperature lower than that of the hot water storage operation mode is heated by the heat pump cycle, and hot water generated by the heat pump cycle is heated. and through the pipe for returning to the upper portion of the hot water storage tank, once the hot water storage tank After entering, via the first tapping pipe includes a hot beam operating mode used for pouring into the bathtub, a, wherein, in the melt-beam operation mode, is hot water storage to the hot water storage tank The heating capacity in the heat pump cycle is reduced when the hot water storage temperature is higher than when the hot water storage temperature is low.

As a result, when the hot water storage temperature is lowered during hot water operation mode, the heating capacity of the heat pump cycle is increased, so the amount of hot water used in the hot water storage tank is reduced, the amount of remaining hot water is ensured, and the risk of running out of hot water is reduced. At the same time, a heat pump water heater excellent in energy saving can be provided.

  According to a second aspect of the invention, in particular, in the first aspect of the invention, the heating capacity of the heat pump cycle in the hot water operation mode is equal to or greater than the heating capacity of the heat pump cycle in the hot water storage operation mode. It is what.

  Thereby, in the hot water operation mode, a minimum compression ratio can be ensured, the reliability of the compressor can be improved, and a heat pump water heater excellent in energy saving can be provided.

  The third invention is characterized in that, in particular, in the second invention, the rotational speed of the compressor in the hot water operation mode is equal to or higher than the rotational speed of the compressor in the hot water storage operation mode. To do.

  Thereby, in the hot water operation mode, a minimum compression ratio can be ensured, the reliability of the compressor can be improved, and a heat pump water heater excellent in energy saving can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a heat pump water heater in Embodiment 1 of the present invention. The heat pump water heater is composed of a heat pump unit 2a and a hot water storage unit 2b.

  The heat pump unit 2 a is provided with a heat pump cycle 1 in which a compressor 4, a water refrigerant heat exchanger 5, a pressure reducing means 6 such as an electromagnetic expansion valve, and an evaporator 7, which is an air heat exchanger, are annularly connected by refrigerant piping. The refrigerant is enclosed in the refrigerant pipe. A fan 8 supplies air to the evaporator 7. Reference numeral 43 denotes outside air temperature detecting means for detecting the intake air temperature of the evaporator 7. As the refrigerant, carbon dioxide or HFC refrigerant is used. When carbon dioxide is used as a refrigerant, the high-pressure side pressure during operation is equal to or higher than the critical pressure.

  The hot water storage unit 2b is provided with a boiling circuit by connecting the bottom of the hot water storage tank 3, the boiling forward pipe 32, the water refrigerant heat exchanger 5, the boiling return pipe 33, the four-way switching valve 18a, and the hot water storage tank 3 in an annular shape. It has been.

  A boiling pump 21 that conveys the water at the bottom of the hot water storage tank 3 to the water-refrigerant heat exchanger 5 is connected to the middle of the boiling piping 32.

  A boiling return pipe 33 is connected to the inlet side of the four-way switching valve 18a. The outlet side of the four-way switching valve 18a is connected to the bottom of the hot water storage tank 3 by the boiling bypass pipe 34, and the other outlet side of the four-way switching valve 18a is connected to the upper part of the hot water storage tank 3 through the heating pipe 35. The other outlet side of the four-way switching valve 18a is connected to the upper part of the hot water storage tank 3 via the hot water return pipe 36.

  That is, the hot water in the boiling return pipe 33 conveyed by the boiling pump 21 is returned to the bottom of the hot water storage tank 3 by the four-way switching valve 18a, and the upper part of the hot water storage tank 3 (the first outlet pipe 9 or hot water). It is possible to switch between returning to the return pipe 36).

  Further, an incoming water temperature detecting means 41 for detecting the water temperature at the inlet of the water refrigerant heat exchanger 5 and a hot water temperature detecting means 42 as a hot water temperature sensor for detecting the water temperature at the outlet of the water refrigerant heat exchanger 5 are provided.

  A plurality of remaining hot water thermistors (temperature sensors) 40a to 40e as hot water storage temperature detecting means are installed on the wall surface of the hot water storage tank 3, and the amount of heat stored in the hot water storage tank 3 is grasped based on the temperature of the remaining hot water thermistors 40a to 40e. can do.

  Water from the water supply is supplied to the hot water storage tank 3, a third mixing valve 14, and a first mixing valve 15, which will be described later, via a water supply pipe 11 to which a pressure reducing valve 20 is connected. The water supply pipe 11 branches into a second water supply branch pipe 12 a, a third water supply branch pipe 12 b, and a first water supply branch pipe 12 c at the water supply branch section 12, and the second water supply branch pipe 12 a is formed at the bottom of the hot water storage tank 3. The third water supply branch pipe 12 b is connected to the third mixing valve 14, and the first water supply branch pipe 12 c is connected to the first mixing valve 15.

  A first hot water discharge pipe 9 is connected to the upper part of the hot water storage tank 3, and an intermediate temperature hot water supply pipe 10 is connected between the position where the first hot water discharge pipe 9 is connected in the vertical direction of the hot water storage tank 3 and the bottom of the hot water storage tank 3. Has been. The other end of the first hot water pipe 9 branches into a hot water branch pipe 16 and a reheating pipe 25, the hot water branch pipe 16 is connected to the second mixing valve 13, and the reheating pipe 25 is connected to the bath heat exchanger 24. Has been.

  The hot water supply circuit mixes the hot water in the hot water storage tank 3 and the water supplied from the water supply with the second mixing valve 13, the third mixing valve 14, and the first mixing valve 15 to obtain hot water at a predetermined temperature. This is a circuit for supplying hot water to a hot water supply terminal (not shown) such as a shower or a bathtub.

  The second mixing valve 13 mixes the hot water supplied from the first hot water discharge pipe 9 and the hot water supplied from the intermediate hot water hot water pipe 10 and causes the hot water to flow out from the hot water joining pipe 17. The outgoing hot water junction pipe 17 branches into a first outgoing hot water joint pipe branch pipe 17a and a second outgoing hot water joint pipe branch pipe 17b. The first outgoing hot water joint pipe branch pipe 17a is connected to the third mixing valve 14 and the second outgoing hot water joint pipe. The branch pipes 17b are connected to the first mixing valve 15, respectively.

  The third mixing valve 14 mixes hot water supplied from the first outlet hot water merging pipe branch pipe 17a and water supplied from the third water supply branch pipe 12b, and causes the hot water to flow out from the hot water pipe 28 to supply hot water such as a currant or shower. Hot water of a predetermined temperature is supplied from a terminal (not shown).

  The hot water supply pipe 28 connected to the outlet side of the third mixing valve 14 is provided with a hot water supply temperature sensor 43a as a first hot water supply temperature detection means. When hot water is supplied from a hot water supply terminal, the hot water supply temperature sensor 43a detects the hot water supply temperature sensor 43a. The control unit 51 controls the mixing ratio of the third mixing valve 14 so that the temperature becomes the target set temperature. The target set temperature is set by the user from the remote controller 50, for example.

  The first mixing valve 15 mixes the hot water supplied from the second outlet hot water junction branch pipe 17b and the water supplied from the first water supply branch pipe 12c and causes the hot water to flow out from the bath pouring pipe 27. Then, hot water having a predetermined temperature is poured into the bathtub 31 through the bath going-out pipe 29 and the bath return pipe 30.

  The bath pouring pipe 27 connected to the outlet side of the first mixing valve 15 is provided with a bath hot water temperature sensor 43b as a second hot water temperature detecting means. The control means 51 controls the mixing ratio of the third mixing valve 14 so that the detected temperature of the sensor 43b becomes the target set temperature. The target set temperature is set by the user from the remote controller 50, for example.

  The bath reheating circuit can heat the hot water in the bathtub 31 to a predetermined temperature by exchanging heat between the hot water in the hot water storage tank 3 and the hot water in the bathtub 31 by the bath heat exchanger 24.

  The bath reheating circuit is configured by connecting the hot water storage tank 3, the first hot water discharge pipe 9, the reheating pipe 25, the bath heat exchanger 24, the reheating pump 22, the reheating return pipe 26, and the hot water storage tank 3 in a ring shape. A primary circuit, a bathtub 31, a bath return pipe 30, a bath circulation pump 23, a bath heat exchanger 24, a bath outlet pipe 29, and a secondary circuit configured by connecting the bathtub 31 in an annular shape are provided. In the middle of the bath return pipe 30, a bath temperature sensor 45 serving as a bath temperature detecting means for detecting the hot water temperature in the bathtub 31 and a water level sensor 46 serving as a bath water level detecting means are installed.

  Moreover, the heat pump water heater of the present invention includes the heat pump cycle 1 in the hot water storage operation mode in which the hot water heated in the heat pump cycle 1 is stored in the hot water storage tank 3 and the bath hot water in which hot water at a predetermined temperature is applied to the bathtub 31 by a predetermined amount. And a hot water valve operation mode in which hot water supplied from the water-refrigerant heat exchanger 5 and hot water supplied from the first outlet pipe 9 are poured into the hot water beam operation mode. I have. In the present embodiment, the mixed hot water is poured into the bathtub 31 via the second mixing valve 13, the first mixing valve 15, and the bath pouring pipe 27.

  In the hot water operation mode, operation is started by operating the remote controller 50 as setting operation means. For example, it is started by pressing an automatic bath hot water button (not shown) provided on the remote controller 50.

  Operation control of each device in the hot water storage operation mode and the hot water operation mode is performed by the control means 51.

  About the heat pump water heater comprised as mentioned above, operation | movement of the operation mode of a heat pump water heater is demonstrated.

  The hot water storage operation mode is a mode in which the water at the bottom of the hot water storage tank 3 is heated by the heat pump cycle 1 and then stored in the upper part of the hot water storage tank 3. It is normal to use cheap electricity at midnight (23:00 to 7:00 the next morning), but if the amount of hot water in the hot water storage tank 3 decreases and the risk of running out of hot water arises, the daytime There is a case of driving from (7 o'clock to 23 o'clock).

  In the hot water storage operation mode, the refrigerant sealed in the heat pump cycle 1 of the heat pump unit 2a is sucked into the compressor 4 in a low-pressure gas state, compressed into a high-temperature and high-pressure state, and then transferred to the water-refrigerant heat exchanger 5. As a result, heat is exchanged with the water transported from the hot water storage tank 3 and the device itself enters a low temperature and high pressure state.

  Thereafter, the refrigerant becomes a gas-liquid two-phase refrigerant expanded to a low-temperature and low-pressure state by the decompression means 6 such as an expansion valve, and the evaporator 7 absorbs heat from the outside air blown by the fan 8 to become a low-pressure gas refrigerant. Repeatedly inhaling.

  On the other hand, the water at the bottom of the hot water storage tank 3 is conveyed to the water / refrigerant heat exchanger 5 via the boiling forward pipe 32 by the boiling pump 21, and is heated by exchanging heat with the refrigerant of the heat pump cycle 1. It becomes warm water. Thereafter, the heated hot water is returned to the top or bottom of the hot water storage tank 3 through the boiling return pipe 33 and the four-way switching valve 18a.

The outlet temperature of the hot water flowing out from the water-refrigerant heat exchanger 5 does not reach the target hot water temperature immediately after the heat pump cycle 1 is started, but takes a while. While the temperature detected by the hot water temperature detection means 42 (hereinafter referred to as the detected temperature) is lower than the target hot water temperature (for example, when the temperature difference between the target hot water temperature and the detected temperature is greater than or equal to a predetermined value), boiling is performed. The hot water in the return pipe 33 is returned to the bottom of the hot water storage tank 3 through the boiling bypass pipe 34 by the four-way switching valve 18a.

  Thereafter, when the detected temperature approaches the target hot water temperature (for example, when the temperature difference between the target hot water temperature and the detected temperature becomes less than a predetermined value), the four-way switching valve 18a is switched to warm water in the boiling return pipe 33. Is returned to the upper part of the hot water storage tank 3 through the boiling pipe 35 and the first hot water discharge pipe 9. With the above operation, the hot temperature heated in the heat pump cycle 1 is stored in the hot water storage tank 3.

  Next, the operation of the medium temperature hot water by the second mixing valve 13 in the hot water supply circuit will be described with reference to FIG. FIG. 2 shows an example of the temperature distribution in the hot water storage tank 3 after supplying a predetermined amount of hot water from a state where the entire amount of the hot water storage tank 3 is boiled. The solid line in FIG. 2 indicates the case where the medium temperature hot water is performed, and the broken line indicates the case where the medium temperature hot water is not performed.

  When hot water is supplied to the hot water supply terminal or the bathtub 31 at the target hot water supply temperature T1 (° C.) set by the user, hot water supplied from the upper part of the hot water storage tank 3 via the first hot water discharge pipe 9 and the hot water branch pipe 16; Hot water supplied from a substantially central portion of the hot water storage tank 3 via the intermediate hot water discharge pipe 10 is mixed by the second mixing valve 13, and hot water having a temperature higher than the target hot water supply temperature T1 by a predetermined temperature difference δT (K). As shown in FIG.

  When hot water is supplied to the hot water supply terminal at the target hot water supply temperature T1 (° C.), hot water of T1 + δT (° C.) supplied from the second mixing valve 13 via the hot water joining pipe 17 and the first hot water joining pipe branch pipe 17a; The third mixing valve is mixed with the water supplied from the water supply pipe 11 via the second water supply branch pipe 12b by the third mixing valve 14 so that the detected temperature of the hot water supply temperature sensor 43a becomes the target hot water supply temperature T1. 14 is controlled by the control means 51.

  When hot water is supplied to the bathtub 31 at the target hot water supply temperature T1 (° C.), the hot water of T1 + δT (° C.) supplied from the second mixing valve 13 via the hot water joining pipe 17 and the second hot water joining pipe branch pipe 17b. And the water supplied from the water supply pipe 11 via the first water supply branch pipe 12c are mixed by the first mixing valve 15 so that the detected temperature of the bath hot water temperature sensor 43b becomes the target hot water temperature T1. The mixing ratio of the 1 mixing valve 15 is controlled by the control means 51.

  In the present embodiment, the temperature sensor is not installed on the outlet side of the second mixing valve 13, and the hot water temperature supplied from the first hot water discharge pipe 9 and the hot water temperature supplied from the intermediate hot water hot water pipe 10 remain. It is detected by the hot water thermistors 40a to 40e and controlled so that the outlet temperature becomes T1 + δT (° C.). A second mixing valve outlet temperature sensor is added to the outlet of the second mixing valve 13, and this second mixing is performed. The second mixing valve 13 may be controlled so that the temperature detected by the valve outlet temperature sensor becomes T1 + δT (K).

  Through the above operation, the boundary layer between the hot water at the top of the hot water storage tank 3 and the low temperature water at the bottom of the hot water storage tank 3 (hereinafter referred to as “medium temperature layer”) Since the intermediate temperature water (referred to as “warm water”) is discharged from the intermediate temperature hot water discharge pipe 10 to the outside of the hot water storage tank 3, an increase in water temperature (ΔT) at the bottom of the hot water storage tank 3 can be suppressed as shown in FIG.

  As a characteristic of the heat pump cycle 1, it is known that the coefficient of performance (COP) decreases as the inlet water temperature of the water-refrigerant heat exchanger 5 increases. Therefore, by suppressing the rise in the water temperature at the bottom of the hot water storage tank 3 by the medium temperature hot water, it is possible to improve the COP of the heat pump cycle 1 during the boiling operation and to save energy.

  Next, hot water operation to the bathtub 31 will be described.

  FIG. 3 shows a control flowchart at the start of hot water. In FIG. 3, when a hot water bath command is input by the user via the remote controller 50 (step 1), the temperature of the remaining hot water thermistors 40a to 40e installed on the wall surface of the hot water storage tank 3 in order to grasp the remaining hot water amount. Is detected (step 2). Next, in order to determine whether the amount of remaining hot water is large or small, it is compared whether the temperature of the remaining hot water thermistor 40d is higher or lower than a predetermined temperature (step 3).

  For example, when the temperature (T40d) of the remaining hot water thermistor 40d is 60 ° C. or less at step 3, it is determined that the amount of remaining hot water is small, the compressor 4 of the heat pump cycle 1 is operated (step 4), and the hot water from the hot water storage tank 3 is Bath hot water is started in the so-called combined hot water operation mode in which both hot water heated by the heat pump is used to heat the hot water (step 6).

  On the other hand, when the temperature of the remaining hot water thermistor 40d (T40d) is higher than 60 ° C. at step 3, it is determined that the amount of remaining hot water is large, and the compressor 4 of the heat pump cycle 1 does not operate (step 5). The so-called normal hot water operation mode in which the hot water bath is heated only (step 6).

  FIG. 4 shows a control sequence in the hot water operation mode. In FIG. 4, when a bath hot water command is input by the user via the remote controller 50, the remaining hot water amount is detected as shown in FIG. 3, and when it is determined that the remaining hot water amount is small, the compressor 4 is started. Thus, the heat pump cycle 1 is activated and the boiling pump 21 is operated. Note that the detection value of the remaining hot water thermistor 40d located at a position higher than the medium temperature hot water discharge pipe 10 may be directly used to determine whether or not to perform the combined hot water operation mode. The determination may be made based on the amount of stored hot water (stored heat) in the hot water storage tank 3. That is, when the amount of heat stored in the hot water storage tank 3 is less than a predetermined value, the combined hot water operation mode is executed, and when the amount of stored heat is small, the heating capacity of the heat pump cycle 1 is increased. It may be.

  In addition, the pouring valve 19 is opened, and the four-way switching valve 18a is switched so that the boiling return pipe 33 and the hot water return pipe 36 communicate with each other.

  By this operation, the water at the bottom of the hot water storage tank 3 is conveyed to the water / refrigerant heat exchanger 5 by the boiling pump 21, where it is heated and exchanged with the refrigerant of the heat pump cycle 1, and then heated to the boiling return pipe 33. It passes through the four-way switching valve 18 a and the hot water return pipe 36 and once enters the hot water storage tank 3. Thereafter, it is mixed with hot water in the hot water storage tank 3, and the first outlet pipe 9, the second mixing valve 13, the first mixing valve 15, the bath pouring pipe 27, the pouring valve 19, the bath outlet pipe 29, and the bath return pipe 30. The hot water is poured into the bathtub 31 via

  At the beginning of the heat pump cycle 1, the outlet water temperature of the water-refrigerant heat exchanger 5 does not rise immediately, but after passing through the hot water return pipe 36, it once enters the hot water storage tank 3 and mixes with the hot water in the hot water storage tank 3. Then, since it is mixed with the hot water supplied via the first hot water discharge pipe 9, it does not fall below the target hot water supply temperature.

  FIG. 5 shows the relationship between the coefficient of performance (COP) of the heat pump cycle and the tapping temperature. Here, the coefficient of performance (COP) of the heat pump cycle in the hot water storage operation mode is represented by COPA, and the coefficient of performance (COP) of the heat pump cycle in the combined hot water beam operation mode is represented by COPB.

  The hot water temperature in the hot water storage operation mode (detected temperature of the hot water temperature detection means 42) is generally 65 ° C. to 90 ° C., but the hot water temperature in the hot water operation mode is lower than the hot water temperature in the hot water operation mode (for example, , 35 ° C.), COPB can be improved over COPA and energy can be saved.

  As a specific means for lowering the hot water temperature in the hot water operation mode to be lower than the hot water temperature in the hot water operation mode, increasing the flow rate by increasing the rotation speed of the boiling pump 21 than in the hot water operation mode. Thus, the outlet temperature of the water-refrigerant heat exchanger 5 can be made lower than the outlet temperature in the hot water storage operation mode.

  FIG. 6 shows the relationship between the heating capacity of the heat pump cycle 1 and the compression ratio in the hot water operation mode. When the rotation speed of the compressor 4 is the same, the higher the compression ratio, the higher the discharge pressure, and the higher the discharge temperature and the higher the heating capacity. However, the characteristics increase slightly to the right (solid line).

  Furthermore, when the tapping temperature is the same, the discharge pressure is almost the same regardless of the heating capacity, but the higher the heating capacity, the higher the rotation speed of the compressor 4 and the lower the suction pressure, so the compression ratio increases. It becomes the characteristic of rising to the right (dashed line).

  For example, if the compression ratio that can ensure the reliability of the compressor 4 is d (broken line), it can be seen that the lower the heating capacity, the lower the rotation speed of the compressor 4 but the higher the hot water temperature.

  FIG. 7 shows the relationship between the heating capacity of the heat pump cycle 1 in the combined hot water operation mode and COPB, which is the coefficient of performance (COP) of the heat pump cycle in the combined hot water operation mode. In the compression ratio d in FIG. 6, when the heating capacity in the hot water storage operation mode is 4.5 (kW), COPB peaks at e1 (kW) lower than the heating capacity.

  However, in the combined hot water operation mode, the hot water from the hot water storage tank 3 and the hot water from the heat pump cycle 1 are used in combination, so that if the heating capacity of the heat pump cycle 1 is low, a large amount of hot water from the hot water storage tank 3 is required. It becomes.

  FIG. 8 shows the relationship between the heating capacity of the heat pump cycle 1 and the bath pouring COP in the combined hot water beam operation mode. Here, the bath pouring COP is represented by (Equation 1).

風呂注湯ＣＯＰは、貯湯運転モードにおけるＣＯＰＡ（例えば、加熱能力が４．５ｋＷ）、湯はり時に貯湯タンク３から使用した熱量、併用湯はり運転モードにおけるＣＯＰＢ（例えば、加熱能力を３．０ｋＷ、３．５ｋＷ、４．０ｋＷ、４．５ｋＷ、５．０ｋＷ）と湯はり時にヒートポンプサイクル１で沸き上げた熱量および湯はり熱量で表される。

The bath pouring COP is COPA in the hot water storage operation mode (for example, heating capacity is 4.5 kW), the amount of heat used from the hot water storage tank 3 during hot water filling, and the COPB in the combined hot water operation mode (for example, heating capacity is 3.0 kW, (3.5 kW, 4.0 kW, 4.5 kW, 5.0 kW), and expressed by the amount of heat boiled in the heat pump cycle 1 and the amount of hot water.

Here, the hot water heat amount is the heat amount of hot water that has entered the bathtub 31, and is represented by the sum of the heat amount used from the hot water storage tank 3 and the heat amount boiled in the heat pump cycle 1. The amount of heat boiled in the heat pump cycle 1 is calculated by the product of the heating capacity of the heat pump cycle 1 and the operation time. Therefore, the amount of heat used from the hot water storage tank 3 is calculated as the difference between the amount of heat of the hot water that has entered the bathtub 31 and the amount of heat that has been boiled in the heat pump cycle 1.

  As can be seen from FIG. 8, when the heating capacity in the hot water storage operation mode is 4.5 (kW), the bath pouring COP peaks at e2 (kW) which is larger than the heating capacity.

  FIG. 9 shows the relationship between the rotational speed of the compressor 4 and the bath pouring COP in the hot water operation mode. Similar to FIG. 8, for example, the compressor rotation speed is changed to 30 Hz, 35 Hz, 40 Hz, 45 Hz, and 50 Hz, and the bath pouring COP is calculated from the heating capability for each rotation speed.

  As can be seen from FIG. 9, the bath pouring COP has a peak at e3 (Hz) higher than the rotational speed when the rotational speed of the compressor 4 in the hot water storage operation mode is 45 (Hz), for example.

  FIGS. 10A and 10B are examples showing the relationship between the hot water storage temperature and the heating capacity in the combined hot water beam operation mode. FIG. 10A shows a case where the heating capacity is set to be small when the hot water storage temperature is high. FIG.10 (b) is a case where it sets so that a heating capability may become large when hot water storage temperature becomes high.

  FIG. 11 is an example showing the relationship between the hot water storage temperature before being poured into the bathtub and the remaining hot water amount in the hot water storage operation mode. Generally, when the outside air temperature decreases, the hot water storage temperature increases and the amount of remaining hot water increases.

  FIG. 12 (a) is an example showing the amount of remaining hot water after being poured into the bathtub in the hot water operation mode (when the heating capacity is set to decrease when the hot water storage temperature increases).

  Here, ◯ indicates the state before pouring into the bathtub (same as in FIG. 11), △ indicates the case where the bath is poured without operating the heat pump cycle, and □ indicates the heat pump cycle. This shows the case where the tub is poured and the hot water is poured into the bathtub. Therefore, the increase in the amount of remaining hot water from the Δ mark to the □ mark corresponds to the product of the heating capacity and the operation time of the heat pump cycle shown in FIG. Since the heating capacity is set to decrease as the hot water storage temperature increases, the increase in the amount of remaining hot water from the Δ mark to the □ mark increases as the hot water storage temperature decreases.

  From FIG. 12 (a), it can be seen that the square marks indicate that the remaining hot water amount can be ensured regardless of the hot water storage temperature and that the hot water does not run out.

  FIG. 12B is an example showing the amount of remaining hot water after being poured into the bathtub in the hot water operation mode (when the heating capacity is set to increase as the hot water storage temperature increases).

  Here, as in FIG. 12 (a), the ◯ marks indicate before being poured into the bathtub (same as in FIG. 11), and the △ marks are poured into the bathtub without operating the heat pump cycle. □ indicates the case where the heat pump cycle is operated and the bath is poured. Therefore, the increase in the amount of remaining hot water from the Δ mark to the □ mark corresponds to the product of the heating capacity and the operation time of the heat pump cycle shown in FIG. Since the heating capacity is set to increase as the hot water storage temperature increases, the increase in the amount of remaining hot water from the Δ mark to the □ mark increases as the hot water storage temperature increases.

From this figure, it can be seen that the □ marks indicate that the higher the hot water storage temperature, the easier it is to secure the remaining hot water amount, and that the hot water storage temperature may be low, for example, 65 ° C., the hot water may run out. If the remaining hot water amount before being poured into the bathtub is increased in order to avoid this hot water shortage, the energy saving property is impaired.

  Therefore, like the heat pump water heater in the present embodiment, in the combined hot water operation mode, when the hot water storage temperature is low, the heating capacity of the heat pump cycle is increased, so the amount of hot water used in the hot water storage tank is reduced, The amount of remaining hot water is secured, the risk of running out of hot water is reduced, and a heat pump water heater excellent in energy saving can be provided. In addition to the hot water storage temperature, the heating capacity of the heat pump cycle 1 may be increased or decreased based on the retained heat amount calculated from the plurality of remaining hot water thermistors 40. That is, the heating capacity of the heat pump cycle 1 may be increased when the amount of retained heat is smaller than when the amount of retained heat is large.

  Next, the stop time of the combined hot water operation mode will be described.

  FIG. 13 shows a control flowchart when the combined hot water beam operation mode is stopped. In FIG. 13, when a predetermined amount of hot water is applied by the water level sensor 46 or the like in the hot water bath operation (step 1) in the combined hot water operation mode, when the hot water hot water completion is detected (step 2), the remaining hot water amount is grasped. Therefore, the temperature of the remaining hot water thermistors 40a to 40e installed on the wall surface of the hot water storage tank 3 is detected (step 3).

  Next, in order to determine whether the amount of remaining hot water is large or small, it is compared whether the temperature of the remaining hot water thermistor 40b is higher or lower than a predetermined temperature (step 4). For example, in step 4, when the temperature (T40b) of the remaining hot water thermistor 40b is less than 60 ° C., it is determined that the amount of remaining hot water is small, and the hot pump operation mode is shifted to the hot water storage operation mode without stopping the operation of the heat pump. (Step 5). In the hot water storage operation mode, when a predetermined condition is satisfied, the hot water storage operation is completed (step 6), and the operation of the compressor 4 of the heat pump cycle 1 is stopped (step 7).

  On the other hand, when the temperature (T40b) of the remaining hot water thermistor 40b is 60 ° C. or more at step 4, it is determined that the amount of remaining hot water is large, and the operation of the compressor 4 of the heat pump cycle 1 is stopped (step 7).

  Therefore, when the amount of remaining hot water is small, the compressor is shifted from the hot water operation mode to the hot water storage operation mode without stopping, so that the start-up loss can be reduced as compared with the case of newly operating in the hot water storage operation mode. Further, when the amount of remaining hot water is large, the hot water operation mode is completed and the operation of the compressor is stopped, so that energy loss due to excess hot water can be reduced.

  Fig.14 (a) is the figure which showed the change of the temperature distribution in the hot water storage tank in case there exists an intermediate temperature hot-water supply circuit. 61 is the temperature distribution before performing hot water in the hot water operation mode, 62 is the temperature distribution after performing hot water in the hot water operation mode, and 63 is the temperature distribution after performing hot water supply and boiling operation thereafter. Show.

  By performing hot water heating in the hot water operation mode, the temperature of the upper part of the hot water storage tank 3 decreases (61 → 62). Thereafter, by performing hot water supply and boiling operation while performing medium temperature hot water, the angle of the temperature distribution changes from α → β (β> α) (62 → 63). This means that the temperature distribution deteriorated by hot water in hot water operation mode has been improved by the medium temperature hot water, and it is possible to avoid a decrease in the efficiency of the subsequent night boiling operation and save energy. Sex is not impaired.

FIG. 14 (b) is a diagram showing a change in temperature distribution in the hot water storage tank when there is no medium temperature hot water supply circuit. 61 is the temperature distribution before performing hot water in the hot water operation mode, 64 is the temperature distribution after performing hot water in the hot water operation mode, and 65 is the temperature distribution after performing hot water supply and boiling operation thereafter. Show.

  By performing hot water heating in the hot water operation mode, the temperature of the upper part of the hot water storage tank 3 decreases (61 → 64). Thereafter, even if hot water supply or boiling operation is performed, the angle of temperature distribution does not change γ (β> α> γ) (64 → 65). This means that the temperature distribution deteriorated by performing hot water in hot water operation mode could not be improved because there was no intermediate temperature hot water circuit, and the efficiency of night boiling operation performed thereafter was reduced. Energy conservation will be impaired.

  Accordingly, since the intermediate temperature hot water supply circuit is provided, the hot water is poured in the hot water operation mode, the temperature distribution of the hot water storage tank 3 that is slightly broken can be improved, the lowering of the operation efficiency of the heat pump unit 2 can be avoided, and the energy is saved. Sex is not impaired.

(Embodiment 2)
FIG. 15 is a configuration diagram of a heat pump water heater in Embodiment 2 of the present invention.

  The difference of the second embodiment from the first embodiment is that the hot water return pipe 36 is shared with the boiling pipe 35, and the four-way switching valve 18a is replaced with the three-way switching valve 18b. That's right.

  Thus, according to the 2nd Embodiment of this invention, the hot water return pipe | tube 36 can be reduced and the same effect can be acquired at low cost.

  In the embodiment so far, in the hot water operation mode, the hot water heated in the heat pump cycle 1 is caused to flow into the hot water storage tank 3 through the boiling pipe 35 or the hot water return pipe 36. The same effect can be obtained with a configuration connected to the first tap pipe 9 as in the conventional configuration diagram.

  As described above, since the heat pump water heater according to the present invention can improve energy saving while reducing the risk of running out of hot water, it is useful as a heat pump water heater for home and business use.

DESCRIPTION OF SYMBOLS 1 Heat pump cycle 3 Hot water storage tank 4 Compressor 5 Water refrigerant | coolant heat exchanger 6 Pressure reducing means 7 Evaporator 9 1st hot water pipe 10 Medium temperature hot water pipe 11 Water supply pipe 12 Water supply branch part 13 2nd mixing valve (intermediate mixing valve)
14 Third mixing valve (hot water mixing valve)
15 First mixing valve (bath mixing valve)
16 Hot water branch pipe 17 Hot water junction pipe 18a Four-way switching valve 19 Hot water valve 20 Pressure reducing valve 21 Boiling pump 27 Bath pouring pipe 28 Hot water pipe 31 Bath 32 Heating pipe 33 Heating return pipe 40a-40e Hot water storage temperature detection means (Remaining hot water thermistor)
41 Incoming water temperature detecting means 42 Hot water temperature detecting means (hot water temperature sensor)
43 Outside air temperature detection means 51 Control means

Claims (3)

A heat pump cycle in which a compressor, a water refrigerant heat exchanger, a decompression means, and an evaporator are connected by refrigerant piping;
A hot water storage tank for storing hot water heated and generated by the heat pump cycle;
Piping for returning the hot water generated by heating in the heat pump cycle to the top of the hot water storage tank;
A first hot water pipe for removing hot water from the upper part of the hot water storage tank;
Control means for executing at least a plurality of operation modes,
The plurality of operation modes are:
A hot water storage operation mode in which hot water generated by the heat pump cycle is stored in the hot water storage tank; and
While generating hot water having a temperature lower than that of the hot water storage operation mode by the heat pump cycle, the hot water generated by heating was once introduced into the hot water storage tank through a pipe returning to the upper part of the hot water storage tank. And a hot water beam operation mode used for pouring into the bathtub via the first outlet pipe ,
The control means reduces the heating capacity in the heat pump cycle when the hot water storage temperature of the hot water stored in the hot water storage tank is higher than when the hot water storage temperature is low in the hot water operation mode. Machine. The heat pump water heater according to claim 1, wherein the heating capacity of the heat pump cycle in the hot water operation mode is equal to or greater than the heating capacity of the heat pump cycle in the hot water storage operation mode. The heat pump water heater according to claim 2, wherein the number of revolutions of the compressor in the hot water operation mode is equal to or higher than the number of revolutions of the compressor in the hot water storage operation mode.

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