JP7279350B2 - heat pump water heater - Google Patents

Description

The present invention relates to a heat pump water heater.

In the conventional heat pump water heater disclosed in Patent Literature 1 below, the heating capacity during the boiling operation during the midnight hours is set to be substantially equal to or less than the heating capacity during the daytime hours.

JP 2017-72265 A

The water heater disclosed in Patent Document 1 operates with a reduced heating capacity during the late-night boiling operation. Therefore, if hot water is used in the late-night hours and the amount of hot water to be boiled in the late-night hours increases, there is a possibility that the necessary amount of hot water cannot be boiled in the late-night hours. As for power charges for users of nighttime heat storage devices that store heat during the night, charges per unit power are higher during the daytime than during the nighttime. For this reason, there is a possibility that the power charges for users of heat pump water heaters will increase.

Further, in the prior art, no consideration is given to the increase in boiling time required to boil the same amount of heat when the heating capacity is reduced. In other words, heat radiation from the tank to the outside air from the start of boiling to the completion of boiling is not considered. Therefore, if the heating capacity is reduced, even if the amount of heat heated and generated by the heat pump water heater is the same, the amount of heat stored in the tank after the completion of boiling is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat pump water heater that is advantageous in reliably completing the boiling operation in the middle of the night.

A heat pump water heater according to the present invention has a heat pump cycle for heating water, and controls heating means capable of adjusting heating capacity, a hot water storage tank, and a boiling operation for storing hot water heated by the heating means in the hot water storage tank. and the late-night heating operation includes a plurality of operation modes with different heating capacity values, and when the late-night heating operation is performed, the control means Control is performed so that the heating capacity when the amount of heat required for boiling, which is the amount of heat generated in the heating operation, is small is greater than the heating capacity when the amount of heat required for boiling is small, and the control means performs the boiling operation during midnight hours. is controlled so that its heating capacity is greater than the heating capacity of the boiling operation during the daytime hours.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the heat-pump water heater which becomes advantageous in reliably completing the boiling operation within a midnight time zone.

1 is an overall configuration diagram showing a heat pump water heater according to Embodiment 1. FIG. FIG. 4 is a diagram showing the flow of water and refrigerant during boiling operation in the heat pump water heater according to Embodiment 1; 4 is a control flow chart of a late-night boiling operation in the heat pump water heater according to Embodiment 1. FIG. FIG. 4 is a diagram showing an example of a pattern of a one-day heating operation in the heat pump water heater according to Embodiment 1; FIG. 4 is a diagram showing operating characteristics of a heat pump unit; FIG. 4 is a diagram showing a change in the amount of heat stored in the hot water storage tank with respect to the operating time of the boiling operation in the late-night hours;

Embodiments will be described below with reference to the drawings. Elements that are common or correspond to each figure are denoted by the same reference numerals, and overlapping descriptions are simplified or omitted. In this embodiment, the amount of heat in hot water may be treated as the amount of hot water at a predetermined temperature. That is, in the following description, the notation of the amount of hot water may actually mean the amount of heat.

Embodiment 1.
FIG. 1 is an overall configuration diagram showing a heat pump water heater according to Embodiment 1. FIG. As shown in FIG. 1, the heat pump water heater of the present embodiment is a hot water storage type heat pump water heater provided with a heat pump unit 100 corresponding to heating means for heating water, and a hot water storage unit 200 having a hot water storage tank 11. be. The heat pump unit 100 and the hot water storage unit 200 are connected via pipes 16a and 16k through which water passes, and electrical wiring (not shown).

The heat pump unit 100 has devices such as a compressor 1, a water-refrigerant heat exchanger 2, an expansion valve 3, and an air heat exchanger 4, and operates on electric power. These devices are annularly connected by pipes or the like, and constitute a refrigerant circuit 101 in which the refrigerant is circulated by the compressor 1 . The refrigerant circuit 101 corresponds to a heat pump cycle that heats water. The water-refrigerant heat exchanger 2 exchanges heat between water and refrigerant, and has a water inlet and a water outlet. In the following description, the hot water heated by the heat pump unit 100 may be called "heated water". The water-refrigerant heat exchanger 2 heats water, which has flowed in through an inlet, with a refrigerant, and causes the heated water to flow out through an outlet. Also, the air heat exchanger 4 exchanges heat between the air and the refrigerant. The heat pump unit 100 further includes a fan 5 that blows outside air to the air heat exchanger 4 . In the following description, simply referring to "water" or "hot water" may include liquid water of any temperature, from low-temperature water to high-temperature hot water.

In addition to the hot water storage tank 11, the hot water storage unit 200 includes a circulation pump 6a, a reheating pump 6b, a switching valve 7, a switching valve 8, a switching valve 9, a switching valve 10, and the like. The circulation pump 6 a circulates water (including heated water) in a hot water storage circuit 201 and a reheating circuit 202 to be described later, and sends the water toward the inlet of the water-refrigerant heat exchanger 2 . The circulation pump 6 a forms part of the hot water storage circuit 201 and the reheating circuit 202 . The reheating pump 6 b sends water in a bathtub (not shown) toward the reheating heat exchanger 12 . The switching valve 7 is composed of, for example, an electromagnetically driven four-way valve having four ports of A port, B port, C port and D port. The switching valve 7 constitutes a switching mechanism for switching the flow path of the heated water flowing out from the outlet of the water-refrigerant heat exchanger 2 to the switching valve 8 and the low-temperature water return port 11 e located in the lower part of the hot water storage tank 11 . there is Further, the switching valve 7 constitutes a switching mechanism for returning the hot water flowing out from the high-temperature water outlet 11a in the upper part of the hot water storage tank 11 to the low-temperature water return port 11e.

The switching valve 8 is composed of, for example, an electromagnetically driven four-way valve having four ports of E port, F port, G port, and H port. The switching valve 8 divides the flow path of the water flowing in from the E port into a reheating return port 11c at an intermediate height portion of the hot water storage tank 11, a high temperature water outflow port 11b at an upper portion of the hot water storage tank 11, and a reheating heat exchange port 11c. A switching mechanism for switching to the device 12 is configured. The switching valve 9 is composed of, for example, an electromagnetically driven three-way valve or the like having three ports of an I port, a J port, and a K port. The switching valve 9 allows the water flowing out from the water intake port 11f in the lower part of the hot water storage tank 11 to pass through the circulation pump 6a and flow into the water-refrigerant heat exchanger 2. It constitutes a switching mechanism for switching between a flow path state in which water passes through the circulation pump 6 a and flows into the water-refrigerant heat exchanger 2 .

The switching valve 10 has three ports, an L port, an M port, and an N port. The switching valve 10 selects medium-temperature water taken out from the medium-temperature water outlet 11 d at the middle height of the hot water storage tank 11 or low-temperature water from the water supply end connected to the water source, and flows it to the hot water supply mixing unit 15 . The hot water storage tank 11 stores heated water. The hot water storage tank 11 is located below the hot water storage tank 11, in addition to the high temperature water outlet 11a, the high temperature water outlet 11b, the reheating return port 11c, the medium temperature water outlet 11d, the low temperature water return port 11e, and the water intake 11f. 11 g of water supply ports are provided. The water supply port 11g is connected to the water supply end via a pipe 16p. Low-temperature water supplied from the water supply end flows into the hot water storage tank 11 through the pipe 16p.

The outflow port of the water-refrigerant heat exchanger 2 is connected to the A port of the switching valve 7 via a pipe 16a. The B port of the switching valve 7 is connected to the E port of the switching valve 8 via a pipe 16b. The F port of the switching valve 8 is connected to the high-temperature water outlet 11a through the pipes 16c and 16d. Also, the F port is connected to the primary side inlet of the reheating heat exchanger 12 via the pipe 16c and the pipe 16e. The outlet on the primary side of the reheating heat exchanger 12 is connected to the J port of the switching valve 9 via a pipe 16f. In addition, the outlet on the primary side of the reheating heat exchanger 12 is connected to a flow path connecting the medium-temperature water outlet 11d and the L port of the switching valve 10 via a pipe 16g. The I port of the switching valve 9 is connected to the water intake 11f via a pipe 16h. The K port of the switching valve 9 is connected to the suction port of the circulation pump 6a via a pipe 16j. A discharge port of the circulation pump 6a is connected to an inlet of the water-refrigerant heat exchanger 2 via a pipe 16k. A discharge port of the circulation pump 6a is connected to the C port of the switching valve 7 via a pipe 16l. A D port of the switching valve 7 is connected to the low-temperature water return port 11e via a pipe 16m. The H port of the switching valve 8 is connected to the high-temperature water inlet/outlet 11b via pipes 16n and 16q. The G port of the switching valve 8 is connected to the reheating return port 11c via a pipe 16o.

A circulation pump 6a, a hot water storage tank 11, pipes 16a, 16b, 16h, 16j, 16k, 16n, 16q, and switching valves 7, 8, 9 supply heated water flowing out of the water-refrigerant heat exchanger 2 into the hot water storage tank 11. It constitutes a hot water storage circuit 201 for storing hot water.

The circulation pump 6a, the reheating heat exchanger 12, the pipes 16b, 16d, 16e, 16f, 16j, 16l, 16o, and the switching valves 7, 8, 9 use the reheating heat exchanger 12 to heat the water to be heated on the load side. A reheating circuit 202 for heating is configured.

The water to be heated by the reheating heat exchanger 12 is not limited to the bath water described above, and may be, for example, circulating water for floor heating. The circulation pump 6a does not necessarily need to be installed in the hot water storage unit 200, and may be installed in the heat pump unit 100 side. The high-temperature water inlet/outlet 11b, the medium-temperature water outlet 11d, the pipe 16q, the switching valve 10, and the hot water mixing unit 15 constitute a hot water supply circuit 203 that takes out hot water from the hot water storage tank 11 and supplies hot water to the bathtub or the hot water supply end. there is

In the present embodiment, the heating capacity of refrigerant circuit 101 of heat pump unit 100 can be adjusted. In the following description, the heating capacity of the refrigerant circuit 101 of the heat pump unit 100 may be simply referred to as "heating capacity". The heating capacity corresponds to the amount of heat given to water by the heat pump unit 100 per hour. The unit of heating capacity is kW (kilowatt), for example. The compressor 1 is driven by a drive device (not shown) including, for example, an inverter-controlled DC brushless motor. In this case, it is possible to change the pressure and temperature of the refrigerant discharged from the compressor 1 and change the heating capacity by adjusting the rotational speed of the compressor 1 with the driving device. However, in the heat pump water heater of the present disclosure, it is not necessary to use such a drive device. , the pressure and temperature of the refrigerant to be discharged, or the heating capacity may be changed.

Also, other structures may be added to the compressor 1 . Such other structures include, for example, a container such as a suction muffler that is arranged on the suction side to reduce refrigerant noise, and an oil separator that separates and recovers lubricating oil that has flowed out to the discharge side of the compressor 1. and As the refrigerant for the heat pump unit 100, it is preferable to use a refrigerant capable of discharging hot water at a high temperature, such as carbon dioxide, R410A, propane, or propylene, but the heat pump water heater of the present disclosure is limited to these refrigerants. not something.

Next, the control system of the heat pump water heater will be described. In the following description, the temperature of the heating water flowing out from the water-refrigerant heat exchanger 2 is called "boiling temperature". The heat pump unit 100 includes an incoming water temperature sensor 13a that detects the temperature of water flowing into the water-refrigerant heat exchanger 2, a boiling temperature sensor 13b that detects the boiling temperature, and an outside air temperature around the heat pump unit 100. and an outside air temperature sensor 13c. The boiling temperature sensor 13b is arranged near the outlet of the water-refrigerant heat exchanger 2 . The refrigerant circuit 101 also includes a discharge temperature sensor 13d that detects the temperature of the refrigerant discharged from the compressor 1, a suction temperature sensor 13e that detects the temperature of the refrigerant sucked into the compressor 1, and an air heat exchanger 4. and an evaporating temperature sensor 13f for detecting the temperature of the refrigerant at a position serving as an inlet or an intermediate portion of the. The hot water storage unit 200 is provided with a plurality of hot water storage temperature sensors 13g, 13h, 13i and 13j. The stored hot water temperature sensors 13g, 13h, 13i, and 13j are installed in the hot water storage tank 11 at different height positions, and detect the water temperature in the hot water storage tank 11 at each installation location.

The heat pump water heater of the present embodiment includes control device 14 mounted on heat pump unit 100 and control device 50 mounted on hot water storage unit 200 . Each of the control device 14 and the control device 50 includes a microcomputer or the like. The control device 14 and the control device 50 are connected so as to be able to communicate bidirectionally. In the present embodiment, control device 14 and control device 50 cooperate to control the operation of the heat pump water heater. The control device 14 and the control device 50 correspond to control means for controlling a boiling operation in which hot water heated by the heat pump unit 100 is stored in the hot water storage tank 11 .

Hereinafter, for convenience of explanation, the control device 14 and the control device 50 are collectively referred to simply as the "control device 50". That is, in the following description, it is assumed that the control device 50 executes the processing, but any processing may be executed by the control device 14 alone, or may be executed by the control device 50 alone. Alternatively, the control device 14 and the control device 50 may work together. Further, instead of the control device 14 and the control device 50, for example, the remote controller 51 may execute the processing. In that case, the remote control 51 corresponds to the control means. Further, the control means of the heat pump water heater in the present disclosure is not limited to the configuration in which a plurality of control devices cooperate as in the present embodiment, and may be configured by a single control device.

Two-way communication is possible between the control device 50 and the remote controller 51 by wired communication or wireless communication. Control device 50 and remote controller 51 may be able to communicate via a network. A remote control 51 is an example of a user interface. The remote controller 51 has a display section 51a that displays information and an operation section 51b that is operated by a user. The remote controller 51 may include a touch screen that functions as both the display section 51a and the operation section 51b. By operating the remote controller 51, a person such as a user can remotely control the heat pump water heater and perform various settings. The display unit 51a has a function as notification means for notifying information to a person such as a user. The remote controller 51 in the present embodiment includes the display unit 51a as notification means, but as a modification, it may be provided with other notification means such as a voice guidance device. The remote controller 51 may be installed, for example, on the wall of the kitchen, living room, bathroom, or the like. Alternatively, for example, a portable information terminal such as a smart phone may be configured to have a function as a user interface like the remote controller 51 . A plurality of remote controllers 51 may be capable of communicating with the control device 50 .

The controller 50 receives outputs from various sensors included in the heat pump water heater, information on user's operation of the remote controller 51, and the like. The control device 50 controls the operations of the heat pump unit 100 and the hot water storage unit 200 based on these pieces of input information. For example, the control device 50 controls the operating states of the compressor 1, the circulation pump 6a, and the reheating pump 6b, the opening degree of the expansion valve 3, the switching valve 7, the switching valve 8, the switching valve 9, and the switching valve 10. control the direction of the flow path or switching position. Further, the control device 50 executes a boiling operation, a reheating operation, and the like, as described later. The control device 50 controls the boiling temperature and the heating capacity of the refrigerant circuit 101 during the boiling operation.

The control device 50 may be further communicably connected to an external device (not shown). The external device may be, for example, a HEMS (home energy management system) controller.

In the present embodiment, the late-night time zone is a time zone in which the unit price of electricity is cheaper than other time zones. The late-night time zone is, for example, the time zone from 23:00 to 7:00 the next morning. The daytime time zone is a time zone other than the midnight time zone. The daytime time zone is, for example, the time zone from 7:00 to 23:00. This daytime time zone is a time zone in which the electricity rate unit price is relatively high compared to the late night time zone. However, the late-night time zone and the daytime time zone are not limited to the example in this embodiment, and their start time and end time may change according to the contract with the power supplier. is. The control device 50 stores information on the start times and end times of the late-night time period and the daytime time period. The control device 50 has a timer function and can determine whether the current time is in the midnight time zone or the daytime time zone. Further, the control device 50 may acquire information about the start time and end time of the late-night time zone and the daytime time zone from the remote controller 51 or an external device.

Control device 50 in the present embodiment includes hot water supply heat amount calculation means 52 for calculating the heat amount used for hot water supply (hereinafter referred to as "heat amount used for hot water supply"). The hot water supply heat amount calculation means 52 calculates the water supply temperature detected by the water supply temperature sensor 13k, the hot water supply temperature detected by the hot water supply temperature sensor 13l, the hot water supply temperature detected by the bath hot water supply temperature sensor 13m, and the hot water supply flow rate detected by the hot water supply flow rate sensor 17a. and the hot water supply flow rate detected by the bath hot water supply flow rate sensor 17b, the amount of heat used for hot water supply is calculated. The water supply temperature detected by the water supply temperature sensor 13k is the temperature of the low-temperature water supplied from the water source to the water supply end. The hot water supply temperature detected by the hot water supply temperature sensor 13l is the temperature of the hot water supplied from the hot water supply mixer 15 to the hot water supply end other than the bathtub. The hot water supply temperature detected by bath hot water supply temperature sensor 13m is the temperature of the hot water supplied from hot water supply mixing unit 15 to the bathtub. The hot water supply flow rate detected by the hot water supply flow rate sensor 17a is the flow rate of hot water supplied from the hot water supply mixer 15 to the hot water supply end. The hot water supply flow rate detected by the bath hot water supply flow rate sensor 17b is the flow rate of hot water supplied from the hot water supply mixing unit 15 to the bathtub.

The control device 50 has a function of learning the amount of heat used for hot water supply by storing data related to the amount of heat used for hot water supply calculated by the hot water supply heat amount calculating means 52 for a predetermined period in the past (for example, the past two weeks). For example, the control device 50 learns the amount of heat used for hot water supply by statistically processing the amount of heat used for hot water supply during a predetermined period in the past. Further, control device 50 may learn the amount of heat used for hot water supply for each hour of the day.

The heat pump water heater in the present embodiment may include setting means for enabling setting of the late-night time zone mode. For example, the late-night time zone mode may be set by the user operating the remote controller 51 . Alternatively, the late-night time zone mode may be set when the control device 50 receives a command from an external device such as a HEMS controller. The late-night time period mode corresponds to a mode for reducing the power rate by storing a large amount of heat in the hot water storage tank 11 especially in the late-night time period when the unit price of electricity is low. When the late-night time zone mode is set, the control device 50 sets the heating capacity of the refrigerant circuit 101 to a predetermined maximum heating capacity in the boiling operation in the late-night time zone, and sets the boiling temperature to a predetermined maximum. Control the boiling temperature. As a result, since the heating operation is concentrated in the late-night hours, it is possible to reduce the running cost when the amount of hot water supply is such that the boiling operation in the daytime hours is unnecessary. Note that the maximum boiling temperature may be, for example, 90°C.

Next, referring to FIG. 2, the operation of the heating operation of the heat pump water heater will be described. FIG. 2 is a diagram showing the flow of water and refrigerant during boiling operation in the heat pump water heater according to Embodiment 1. FIG. As shown in FIG. 2, in the boiling operation, the refrigerant circuit 101 and the hot water storage circuit 201 are operated to heat the low-temperature water flowing out of the water intake 11f of the hot water storage tank 11 by the refrigerant circuit 101, thereby exchanging water-refrigerant heat. The high-temperature heated water flowing out from the outlet of the vessel 2 is caused to flow into the hot water storage tank 11 from the high-temperature water outlet 11b.

The boiling operation is further described below. In the refrigerant circuit 101 , the temperature of the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 is lowered while radiating heat to the water flowing through the water-refrigerant heat exchanger 2 . At this time, if the pressure of the high-pressure side refrigerant is equal to or less than the critical pressure, the refrigerant releases heat while being liquefied. The high-pressure, low-temperature refrigerant flowing out of the water-refrigerant heat exchanger 2 is decompressed into a low-pressure gas-liquid two-phase state by passing through the expansion valve 3 . Then, this refrigerant evaporates and becomes gas by absorbing heat from the outside air while circulating inside the air heat exchanger 4 . The low-pressure refrigerant flowing out of the air heat exchanger 4 is sucked into the compressor 1 and circulated. This circulation forms a refrigeration cycle, ie, a heat pump cycle.

A switching valve 7 connects the pipes 16a and 16b to each other, a switching valve 8 connects the pipes 16b and 16n to each other, and a switching valve 9 connects the pipes 16h and 16j to each other. . Thus, the hot water storage circuit 201 is formed. When the circulation pump 6a operates, the water in the hot water storage tank 11 is introduced into the water-refrigerant heat exchanger 2 from the water intake 11f through the pipes 16h, 16j, and 16k. This water is heated by the gas refrigerant in the water-refrigerant heat exchanger 2 and flows out of the water-refrigerant heat exchanger 2 as heated water. This heated water passes through the pipes 16a, 16b, 16n, and 16q and flows into the hot water storage tank 11 from the high-temperature water inlet/outlet 11b. Thus, when the boiling operation is performed, hot water is stored while maintaining a temperature distribution state in which the upper portion of the hot water storage tank 11 is high temperature water and the lower portion is low temperature water.

The hot water storage tank 11 is covered with a heat insulating material (not shown). The heat pump water heater in the present embodiment may include an upper heat insulating material that covers the upper portion of hot water storage tank 11 and a lower heat insulating material that covers hot water storage tank 11 at a position below the upper heat insulating material. In that case, it is desirable that the heat transfer coefficient of the upper heat insulating material is lower than that of the lower heat insulating material. As described above, the hot water storage tank 11 is of a type in which hot water is stored in a layered manner in which the upper portion is high temperature and the lower portion is low temperature. higher than temperature. By making the heat transfer rate of the upper heat insulating material smaller than that of the lower heat insulating material, the heat insulating performance of the upper portion of the hot water storage tank 11 can be particularly enhanced. As a result, it is more advantageous to keep the amount of heat radiation from the hot water storage tank 11 low. In addition, the structure of the lower heat insulating material can be made relatively simple, which is advantageous for cost reduction. The upper heat insulating material may be made thicker than the lower heat insulating material so that the heat transfer rate of the upper heat insulating material is lower than that of the lower heat insulating material. ) may be used for the upper heat insulating material (for example, a vacuum heat insulating material) so that the heat transfer rate of the upper heat insulating material is lower than that of the lower heat insulating material.

Next, the temperature control of the heating water and the heating capacity control of the refrigerant circuit 101 executed by the controller 50 during the boiling operation will be described. First, the temperature control is to feedback-control the rotational speed of the circulation pump 6a so that the boiling temperature detected by the boiling temperature sensor 13b becomes equal to a predetermined target boiling temperature. This feedback control is periodically executed at regular time intervals, for example. In the boiling operation, hot water is stored while the target boiling temperature is set to a predetermined hot water storage target temperature. That is, the target boiling temperature is equal to the stored hot water target temperature. For example, the control device 50 sets the hot water storage target temperature, ie, the target boiling temperature, so that the target heat storage amount can be stored in the hot water storage tank 11 in relation to the capacity of the hot water storage tank 11 . The target heat storage amount is set, for example, based on the operation content of the remote control 51, or calculated based on the past hot water supply usage amount. Further, the control device 50 sets the target hot water storage temperature, ie, the target boiling temperature, within a predetermined range (eg, 65 to 90° C.).

Since the temperature control only controls the flow rate of the heating water flowing in and out of the water-refrigerant heat exchanger 2 , the maximum boiling temperature achieved by temperature control depends on the heating capacity of the refrigerant circuit 101 . Therefore, the refrigerant circuit 101 is required to have a heating capacity capable of realizing the target boiling temperature even when the target boiling temperature is set to the maximum value within the set range (90° C. in the above example). For this reason, in the heating capacity control, for example, a target value (target heating capacity) of the heating capacity that satisfies the above requirements is set based on the amount of residual hot water in the hot water storage tank 11, that is, the amount of residual heat, the temperature of the outside air, the temperature of the water supply, and the like. The rotational speed of the compressor 1 and the like are controlled so that the actual heating capacity of the compressor 101 becomes equal to the target heating capacity. By controlling the heating capacity in this way, the required boiling temperature can be stably secured regardless of how the setting of the target boiling temperature and the external conditions change. Heating capacity control is performed, for example, periodically at regular time intervals. Further, the rotation speed of the compressor 1 is provided with an upper limit rotation speed and a lower limit rotation speed from the viewpoint of durability.

Further, in the present disclosure, as the heat pump unit 100, for example, not only a supercritical heat pump unit in which the refrigerant pressure is equal to or higher than the critical pressure, but also a heat pump unit that operates at a pressure equal to or lower than the critical pressure may be used. In this case, Freon gas, ammonia, or the like may be used as the refrigerant.

Here, in the present embodiment, the heating capacity is not constant, and when the amount of remaining hot water is small, the heating capacity is increased to make it possible to use the hot water in a short time, thereby enhancing the user's convenience. Also, when the amount of residual hot water is large, the heating capacity is reduced to improve energy saving.

In the present embodiment, the boiling operation in the midnight hours includes a plurality of operation modes with different heating capacity values. In the present embodiment, control device 50 performs control such that the heating capacity of the boiling operation during the midnight hours is greater than the heating capacity of the boiling operation during the daytime hours. Thus, even when the amount of remaining hot water is reduced by the user using hot water during the boiling operation in the late night hours, the boiling operation can be completed in the late night hours.

In the following description, the target amount of heat to be generated in the boiling operation in the late-night hours is referred to as "heat amount required for boiling". The control device 50 performs control so that the heating capacity when the heat quantity required for boiling is relatively large is greater than the heating capacity when the heat quantity required for boiling is relatively small. As a result, even when the amount of heat required for boiling is relatively large, the boiling operation can be reliably completed within the late-night hours.

FIG. 3 is a control flowchart of the boiling operation in the late-night hours in the heat pump water heater according to Embodiment 1. FIG. The control device 50 executes the process of the flowchart of FIG. 3, for example, at or just before the start time of the midnight time period. The control device 50 calculates a target heat storage amount to be stored in the hot water storage tank 11 by the end of the late-night time zone according to the learned past hot water usage record and the conditions set by the user. The control device 50 calculates the required heat amount for boiling in the late-night hours from the difference between the target heat storage amount and the current residual heat amount in the hot water storage tank 11 (step S1). At this time, the amount of residual heat in the hot water storage tank 11 is calculated using at least one temperature detected by the hot water storage temperature sensors 13g to 13j.

For example, when the temperature detected by the hot water temperature sensor 13h is 40° C. or less, it is determined that the amount of residual heat in the hot water tank 11 is small. On the other hand, when the temperature detected by the hot water storage temperature sensor 13h is 60° C. or higher, it is determined that the amount of residual heat in the hot water storage tank 11 is large. Here, as an example, the amount of residual heat in the hot water storage tank 11 is determined using the hot water storage temperature sensor 13h, but any one or more of the hot water storage temperature sensors 13g to 13j may be used.

Next, the control device 50 calculates a required boiling time t1, which is the time required for the heat pump unit 100 to generate the necessary amount of heat for boiling with the heating capacity Q1 (step S2). The required boiling time t1 can be obtained, for example, based on a value obtained by dividing the necessary heat quantity for boiling by the heating capacity Q1.

Next, the control device 50 determines that the completion time of the boiling operation predicted from the required boiling time t1 is a predetermined time (for example, one hour) or longer than the end time of the late-night time zone (for example, 7:00 am). It is determined whether or not it will be faster (step S3). The boiling operation completion time predicted from the required boiling time t1 is, for example, the time after the start time of the late-night time zone by the required boiling time t1. In the following description, the time earlier than the end time of the late-night time zone by the predetermined time is referred to as the target end time.

If the amount of heat required for boiling is appropriate for the heating capacity Q1 and the predicted boiling operation completion time is earlier than the end time of the late-night time zone by the predetermined time or more, the control device 50 controls the heat pump unit 100 is set to Q1 and the boiling operation is performed (step S4). In this case, the control device 50 may start the boiling operation at a time earlier than the target end time by the required boiling time t1.

On the other hand, if the amount of heat required for boiling is excessive relative to the heating capacity Q1, and the predicted boiling operation completion time is not earlier than the end time of the late-night time zone by the predetermined time or more, control device 50 calculates the required boiling time t2, which is the time required for the heat pump unit 100 to generate the required amount of heat for boiling with the heating capacity Q2 (step S5). Here, heating capacity Q2>heating capacity Q1, and required boiling time t1>boiling required time t2.

Next, the control device 50 determines whether or not the boiling operation completion time predicted from the required boiling time t2 is earlier than the end time of the late-night time period by the predetermined time or more (step S6). ).

If the amount of heat necessary for boiling is appropriate for the heating capacity Q2 and the predicted boiling operation completion time is earlier than the end time of the late-night time period by the predetermined time or more, the control device 50 controls the heat pump unit 100. is set to Q2 and the boiling operation is performed (step S7). In this case, the control device 50 may start the boiling operation at a time earlier than the target end time by the required boiling time t2.

On the other hand, if the amount of heat required for boiling is excessive relative to the heating capacity Q2, and the predicted boiling operation completion time is not earlier than the end time of the late-night time zone by the predetermined time or more, the control device 50 The value of the heating capacity of the heat pump unit 100 is set to Q3 and the boiling operation is performed (step S8). Here, heating capacity Q3>heating capacity Q2. The heating capacity Q3 may be equal to the rated heating capacity Q4. In the following description, it is assumed that the heating capacity Q3<the rated heating capacity Q4. Note that the rated heating capacity Q4 corresponds to, for example, a heating capacity operated under performance evaluation conditions according to JIS.

As described above, in the present embodiment, the control device 50 sets the heating capacity of the boiling operation in the late night time zone to a value that can generate the necessary heat amount for boiling in the late night time zone. control so that That is, the control device 50 performs the boiling operation by increasing the heating capacity as the amount of heat required for boiling increases in the late-night hours. As a result, the boiling operation can be reliably completed within the midnight time zone.

FIG. 4 is a diagram showing an example of a pattern of one-day boiling operation in the heat pump water heater according to Embodiment 1. FIG. FIG. 4 shows an example in which the value of the heating capacity of the heat pump unit 100 is determined as Q3 from the amount of heat necessary for boiling according to the flowchart shown in FIG. 3 at the start of the midnight time period. In the example shown in FIG. 4, the control device 50 controls the value of the heating capacity of the heat pump unit 100 to be Q11 or Q12 during the daytime boiling operation. Here, heating capacity Q11<heating capacity Q12<heating capacity Q1.

As described above, the water heating operation in the daytime hours may include a plurality of operation modes with different heating capacity values. For example, in the boiling operation during daytime hours, the heating capacity value may be set to Q12 when the amount of heat to be generated is relatively large, and the value of heating ability may be set to Q11 when the amount of heat to be generated is relatively small. By doing so, it is possible to avoid increasing the heating capacity more than necessary, so it is possible to operate with a higher COP (coefficient of performance). As a result, it is possible to more reliably suppress an increase in power consumption during the heating operation during the daytime hours. However, the heat pump water heater of the present disclosure is not limited to the above example, and may be one in which the value of the heating capacity of the boiling operation during the daytime hours is fixed at a constant value.

FIG. 5 is a diagram showing operating characteristics of the heat pump unit 100. As shown in FIG. FIG. 5 shows the relationship between the heating capacity of the heat pump unit 100 and the COP, assuming that the heat pump units 100 have the same specifications. As shown in FIG. 5, the heat pump unit 100 has a characteristic that the lower the heating capacity, the higher the COP.

In the case of the heating operation pattern shown in FIG. 4, the heating capacities Q11 and Q12 of the boiling operation during the daytime hours are smaller than the heating capacity Q3 during the midnight hours. Therefore, during the daytime hours, the heat pump unit 100 is operated at a high COP.

On the other hand, the heating capacity Q3 for the boiling operation during the midnight hours is greater than the heating capacities Q11 and Q12 for the boiling operations during the daytime hours. Therefore, even if the hot water is used after determining the value of the heating capacity for the heating operation in the late-night time zone, and the heat quantity required for boiling in the late-night time zone increases, the necessary heat quantity for boiling will not be generated during the late-night time zone. can be completed.

When hot water is used after determining the value of the heating capacity for the boiling operation in the late-night hours, the control device 50 resets the value of the heating capacity by executing the processing of the flowchart of FIG. 3 again. You may

If it is confirmed that the heating capacity exceeding the rated heating capacity Q4 can be operated within the constraint conditions of the equipment of the heat pump unit 100 or the like, the control device 50 controls the heat pump unit. The heating capacity of 100 may be set to a value exceeding the rated heating capacity Q4. In this case, the value of the heating capacity that exceeds the rated heating capacity Q4 and is the maximum within the range in which the devices of the heat pump unit 100 and the like can be operated is hereinafter referred to as "maximum heating capacity".

If the heating capacity of the heat pump unit 100 can be set to a value exceeding the rated heating capacity Q4, the controller 50 may perform the following, for example. Before proceeding from step S6 to step S8 in FIG. 3, the control device 50 calculates a required boiling time t3, which is the time required for the heat pump unit 100 to generate the necessary heat amount for boiling with the heating capacity Q3. Here, the required boiling time t2>the required boiling time t3. Next, the control device 50 determines whether or not the completion time of the boiling operation predicted from the required boiling time t3 is before the end time of the late-night time zone. When the predicted boiling operation completion time is before the end time of the midnight time zone, the control device 50 sets the value of the heating capacity of the heat pump unit 100 to Q3 and performs the boiling operation (step S8). . On the other hand, if the boiling operation completion time predicted from the required boiling time t3 does not come before the end time of the late-night time period, the control device 50 will provide the required heat amount for boiling by the end time of the late-night time period. The value of the heating capacity required for generating is calculated as the required heating capacity. For example, the control device 50 calculates the required heating capacity based on a value obtained by dividing the required heat quantity for boiling by the time from the current time to the end time of the midnight time zone. When the calculated required heating capacity is equal to or less than the rated heating capacity Q4, the control device 50 sets the value of the heating capacity of the heat pump unit 100 to Q4 and performs the boiling operation. On the other hand, when the calculated required heating capacity exceeds the rated heating capacity Q4, the control device 50 sets the value of the heating capacity of the heat pump unit 100 to the maximum heating capacity and performs the boiling operation. By doing so, it is possible to more reliably complete the boiling operation in the late-night time period, thereby more reliably preventing an increase in power charges.

FIG. 6 is a diagram showing changes in the amount of heat stored in the hot water storage tank 11 with respect to the operation time of the boiling operation in the midnight hours. FIG. 6 compares the case where the heating capacity is set to Q1 and the case where the heating capacity is set to Q2 when the required heat quantity for boiling is the same.

In order to complete the generation of heat required for boiling within the midnight hours, the start time of the boiling operation is earlier when operating with the heating capacity Q1 than when operating with the heating capacity Q2. In FIG. 6 , the solid line indicates changes in the amount of heat stored in hot water storage tank 11 in an ideal state in which heat is not radiated from hot water storage tank 11 to the outside air. Assuming that there is no heat release from the hot water storage tank 11 to the outside air, the heating capacity Q1 and the heating capacity Q2 differ in the start time of the boiling operation, but the amount of heat stored in the hot water storage tank 11 increases as the operation time elapses. However, the amount of heat stored in the hot water storage tank 11 at the completion of the boiling operation is the same.

However, actually, heat is radiated from the hot water storage tank 11 to the outside air. In FIG. 6, the dashed line indicates changes in the amount of heat stored in the hot water storage tank 11 when heat is radiated from the hot water storage tank 11 to the outside air. Since heat is radiated from the hot water storage tank 11 to the outside air, the amount of heat stored in the hot water storage tank 11 increases as the operating time elapses, but the increase is lower than the increase in the amount of stored heat indicated by the solid line. In addition, since the operation start time is earlier when operating with the heating capacity Q1 than when operating with the heating capacity Q2, the amount of heat released when operating with the heating capacity Q1 is larger than the amount of heat released when operating with the heating capacity Q2. become more. Therefore, the amount of heat stored in the hot water storage tank 11 at the completion of the boiling operation is greater when operating with the heating capacity Q2 than with the heating capacity Q1.

As described above, considering the heat radiation from the hot water storage tank 11 to the outside air, it is advantageous to increase the heating capacity of the boiling operation in the midnight hours in that the amount of heat radiation from the hot water storage tank 11 to the outside air can be reduced. . In the present embodiment, the amount of heat released from the hot water storage tank 11 to the outside air is reduced by controlling the heating capacity of the boiling operation during the midnight hours to be greater than the heating capacity of the boiling operation during the daytime hours. It is advantageous in reducing

In general, heat pump water heaters tend to require a long period of time from the completion of the boiling operation in the middle of the night to the time when the user uses a lot of hot water, such as filling a bathtub with hot water. Therefore, the shorter the boiling operation time in the late-night time zone and the closer the boiling-up operation completion time is to the end time of the late-night time zone, the less heat is radiated from the hot water storage tank 11 to the outside air, and the heat pump unit 100 hot water can be used more efficiently.

The heat pump water heater of the present embodiment may include notification means for notifying the user of information regarding the heating capacity during the boiling operation. As such notification means, for example, the display unit 51a of the remote controller 51 may display information regarding the value or magnitude of the heating capacity during the boiling operation. This provides excellent convenience.

The heat pump water heater of the present embodiment may include selection means for enabling or disabling the variable heating capacity mode by a user or other person. As such a selection means, for example, it is possible to select whether to enable or disable the variable heating capacity mode by operating a button on the remote controller 51. The heating capacity may be made variable only when the mode is enabled. There are cases where it is required that the heating capacity does not fluctuate, such as at the time of equipment verification to confirm the operation and performance of the equipment. In such a case, by disabling the variable heating capacity mode, it is possible to easily perform an operation to prevent fluctuations in the heating capacity.

In the present embodiment, the controller 50 controls the number of revolutions of the compressor 1 at the start of the boiling operation in the late-night time zone, and the compressor after the boiling temperature reaches the target boiling temperature in the boiling operation. You may control so that it may become higher than 1 rotation speed. By doing so, the following effects can be obtained. Since the temperature of the compressor 1 and the temperature of the water-refrigerant heat exchanger 2 are low at the start of the boiling operation, the temperature of the compressor 1 and the temperature of the water-refrigerant heat exchanger 2 rise, and the boiling temperature reaches the target boiling. It takes some time to reach the temperature. The time is longer as the rotation speed of the compressor 1 is lower. The longer the time it takes for the boiling temperature to reach the target boiling temperature, the more medium-temperature water flows into the hot water storage tank 11 . It is not preferable for the amount of medium-temperature water in the hot water storage tank 11 to increase. Therefore, by increasing the rotational speed of the compressor 1 until the boiling temperature reaches the target boiling temperature, the time until the boiling temperature reaches the target boiling temperature can be shortened. As a result, the amount of intermediate hot water generated in the hot water storage tank 11 can be reduced. In the case of controlling as described above, the heating capacity after the boiling temperature reaches the target boiling temperature corresponds to the heating capacity of the boiling operation in the late-night hours.

In the present embodiment, control device 50 is configured such that the total amount of power consumption during the heating operation during the late-night hours is greater than the total amount of power consumption during the heating operation during the daytime hours. can be controlled to Thereby, an electricity bill can be suppressed more reliably.

1 compressor 2 water refrigerant heat exchanger 3 expansion valve 4 air heat exchanger 5 fan 6a circulation pump 6b reheating pump 7, 8, 9 switching valve 10 switching valve 11 hot water storage tank 11a hot water outlet 11b hot water outlet 11c reheating return 11d middle water outlet 11e low temperature water return 11f water intake 11g water supply 12 reheating heat exchanger 13a inlet water temperature sensor 13b Temperature sensor 13c Outside air temperature sensor 13d Discharge temperature sensor 13e Suction temperature sensor 13f Evaporation temperature sensor 13g, 13h, 13i, 13j Storage hot water temperature sensor 13k Water supply temperature sensor 13l Hot water supply temperature sensor 13m Bath hot water supply temperature sensor 14 control device 15 hot water supply mixing unit 17a hot water supply flow sensor 17b bath hot water supply flow sensor 50 control device 51 remote control 51a display unit 51b operation unit 52 hot water supply heat amount calculation means 100 heat pump unit 101 refrigerant circuit 200 hot water storage unit 201 hot water storage circuit 202 reheating circuit 203 hot water supply circuit

Claims (10)

a heating means having a heat pump cycle for heating water and capable of adjusting the heating capacity;
a water storage tank;
a control means for controlling a boiling operation in which the hot water heated by the heating means is stored in the hot water storage tank;
with
The boiling operation in the midnight time zone includes a plurality of operation modes with different heating capacity values,
During the boiling operation in the late-night time zone, the control means controls the heating capacity to be higher than the heating capacity when the amount of heat required for boiling, which is the amount of heat generated in the boiling operation in the late-night time zone, is small. Control so that the heating capacity is increased when the required amount of heat is large,
The control means controls the heat pump water heater so that the heating capacity of the boiling operation in the midnight time zone is greater than the heating capacity of the boiling operation in the daytime time zone. 2. The control device according to claim 1, wherein the control means controls the heating capacity of the boiling operation in the midnight time zone to a value that enables the heat quantity required for boiling to be generated in the late night time zone. heat pump water heater. 3. The heat pump water heater according to claim 1, wherein said control means can set said heating capacity to a value exceeding a rated heating capacity. The heat pump water heater according to any one of claims 1 to 3, wherein the water heating operation during the daytime includes a plurality of operation modes with different values of the heating capacity. The heating means has a compressor that compresses a refrigerant,
The control means controls that the rotation speed of the compressor at the start of the boiling operation in the midnight time zone reaches a target temperature, which is the temperature of the hot water flowing out of the heating means during the boiling operation. The heat pump water heater according to any one of claims 1 to 4, wherein the heat pump water heater is controlled to be higher than the rotation speed of the compressor after the compression. The control means controls the total amount of power consumption in the heating operation during the late-night time period to be greater than the total amount of power consumption during the heating operation during the daytime period. Item 6. The heat pump water heater according to any one of Items 5. an upper heat insulating material covering the upper portion of the hot water storage tank;
a lower heat insulating material covering the hot water storage tank at a position below the upper heat insulating material;
with
The heat pump water heater according to any one of claims 1 to 6, wherein the heat transfer rate of the upper heat insulating material is smaller than the heat transfer rate of the lower heat insulating material. Equipped with a setting means that can set a late-night time zone mode,
When the late-night time zone mode is set, in the boiling operation during the late-night time zone, the control means sets the heating capacity to the maximum heating capacity, and sets the temperature of the hot water flowing out of the heating means. 8. The heat pump water heater according to any one of claims 1 to 7, wherein the boiling temperature is controlled so as to reach a predetermined maximum temperature. 9. The heat pump water heater according to any one of claims 1 to 8, further comprising notification means for notifying a user of information regarding said heating capacity during said boiling operation. 10. The heat pump water heater according to any one of claims 1 to 9, further comprising selection means capable of selecting whether to enable or disable a plurality of operation modes having different heating capacity values.

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