JP7151442B2 - 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 2017-83045 A

The water heater disclosed in Patent Document 1 is operated 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 a hot water supply heat amount calculation means for calculating the heat amount used for hot water supply, the heating operation in the late-night hours includes a plurality of operation modes with different heating capacity values, and the control means is configured to supply hot water Based on the value calculated by the heat quantity calculating means, the late-night heat quantity used, which is a predicted value of the heat quantity used in the late-night time zone, is calculated. By subtracting the amount of residual heat in the hot water storage tank from the target amount of heat that must be stored in the hot water storage tank by the end of , add the amount of heat used late at night to calculate the amount of heat required for boiling. Control is performed so that the heating capacity when the amount of heat required for boiling is large is greater than the heating capacity when the amount of heat is small, and the control means controls the heating capacity of the boiling operation during the late night hours to be the same as the heating capacity during the daytime hours. is controlled to be greater than the heating capacity of

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the heat-pump water heater which is advantageous in reliably completing the boiling operation in the middle of the night.

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 the relationship between the heating capacity of the heat pump unit and the COP; FIG. 5 is a diagram showing temporal changes in the boiling temperature after the boiling operation is started in the late-night hours. FIG. 5 is a diagram showing an example of changes in temperature distribution in the hot water storage tank before and after the boiling operation is completed in a late-night time zone; FIG. 10 is a diagram showing the remote control when the value of the heating capacity during the boiling operation is displayed on the display unit;

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 flows, 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 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 mixes the medium-temperature water taken out from the medium-temperature water outlet 11d in the middle height portion of the hot water storage tank 11 with the low-temperature water from the water supply end connected to the water source, or mixes the medium-temperature water and the low-temperature water. It is switched to flow out 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 mixing unit 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, the running cost can be reduced when the amount of hot water used 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 low-temperature water flowing out from 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 gasifies by absorbing heat from the outside air while circulating in 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, 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. In this manner, 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". In the present embodiment, 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.

The operation of the heat pump water heater configured as above will be described below. As a basic method of controlling the boiling operation, the boiling operation is mainly performed during the late-night hours, which are non-active hours, to prepare for the use of hot water during the daytime hours of the next day. In the heat pump unit 100, the fan 5 is rotated to supply the heat of the air to the refrigerant flowing through the air heat exchanger 4, and the expansion valve 3 corresponding to the pressure reducing means discharges the refrigerant from the compressor 1. is adjusting the temperature of

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. Based on the amount of residual heat in the hot water storage tank 11 before the start of the boiling operation in the late-night time zone and the learned past hot water usage record, the control device 50 prepares for the next day's use by the end of the late-night time zone. The amount of heat required to be stored in the hot water storage tank 11 (hereinafter referred to as "target heat storage amount") is calculated (step S1).

The amount of remaining hot water or the amount of remaining heat is grasped using at least one or more temperatures detected by the stored hot water temperature sensors 13g to 13j. For example, using the stored hot water temperature sensor 13h and the stored hot water temperature sensor 13j, the temperature difference (Th-Tj) between these values is less than a predetermined value α (for example, 3 deg), and the stored hot water temperature sensor 13j corresponding to the lower side thereof When the value Tj exceeds a predetermined value β (for example, 60° C.), it can be determined that there is hot water from the top surface of the hot water tank 11 to the position of the hot water temperature sensor 13j.

When the temperature of the stored hot water temperature sensor 13j is 60° C. or less, it is determined that the amount of remaining hot water or the amount of residual heat is small. It can be determined that there is hot water up to the position of the sensor 13j.

It should be noted that the accuracy of calculating the residual heat amount using a plurality of stored hot water temperature sensors is better, but in the hot water storage tank 11 of the temperature stratification type in which hot water is stored with a higher temperature in the upper part than in the lower part, the stored hot water is In the height direction of the tank 11, it is desirable to determine the temperature using the temperature of the stored hot water temperature sensor 13j disposed at least between the approximately center portion and the bottom portion.

Subsequently, the control device 50 calculates a late-night heat usage amount, which is a predicted value of the heat amount to be used in the late-night hours of the day, based on the value calculated by the hot water supply heat amount calculation means 52 (step S2). For example, the control device 50 calculates the late-night heat consumption by statistically processing the data of the hot-water supply heat consumption in the late-night hours every day for a predetermined period in the past. In this case, control device 50 may calculate the late-night heat consumption based on the average value or the maximum value of the heat consumption for hot water supply in the late-night hours every day for the past predetermined period.

Next, the control device 50 calculates the required heat amount for boiling using the target heat storage amount and residual heat amount calculated in step S1 and the late-night heat consumption predicted in step S2 (step S3). For example, the control device 50 calculates the required heat amount for boiling by adding the late-night use heat amount to a value obtained by subtracting the residual heat amount from the target heat storage amount. In this way, the control device 50 calculates the heat quantity required for boiling so that the heat quantity required for boiling increases as the late-night heat quantity used increases.

In this embodiment, the value of the heating capacity in the boiling operation in the late-night hours can be adjusted to Q1, Q2, and Q3. Here, Q1<Q2<Q3. Q1 corresponds to the rated heating capacity. This rated heating capacity Q1 may be the value of the heating capacity when operating under the performance evaluation conditions according to JIS, for example. In this embodiment, the boiling operation can be performed with the heating capacity Q2 or the heating capacity Q3 exceeding the rated heating capacity Q1. For example, if it is confirmed that the heating capacity exceeding the rated heating capacity Q1 can be operated within the constraint conditions of the equipment of the heat pump unit 100, etc., the heating capacity exceeding the rated heating capacity Q1 is used. It is possible to perform boiling operation.

In the present embodiment, when the rated heating capacity Q1 cannot generate the heat required for boiling during the midnight hours, the control device 50 sets the heating capacity to a value exceeding the rated heating capacity Q1. The heating capacity is set to Q2 or Q3, and the boiling operation is performed in the late-night hours. This makes it possible to more reliably complete the boiling operation during the midnight hours.

It should be noted that the method by which the controller 50 sets the amount of heat necessary for boiling is not limited to the method from step S1 to step S3. For example, the amount of heat necessary for boiling may be set based on information received by the control device 50 from an external device such as a remote controller 51 or a HEMS controller.

Further, when the late-night time period mode described above is set, the control device 50 sets the heat amount necessary for boiling to the highest value. As a result, by following the flow chart of FIG. 3, the highest heating capacity (heating capacity Q3) among the different heating capacity operation modes that can be set in the late-night hours is set, and the boiling temperature is set to the predetermined highest boiling temperature. set.

In the flowchart of FIG. 3, following the process of step S3, the control device 50 calculates the required boiling time t1, which is the time required for the heat pump unit 100 to generate the required amount of heat for boiling at the rated heating capacity Q1. (step S4). The required boiling time t1 can be obtained, for example, based on a value obtained by dividing the heat quantity required for boiling by the rated heating capacity Q1.

In the following description, the target time for ending the boiling operation in the late-night hours is referred to as "target end time". The target end time may be the same time as the end time of the late-night time period (for example, 7:00 the next morning), or may be a predetermined time (for example, one hour) earlier than the end time of the late-night time period.

Following the process of step S4, the control device 50 determines whether or not the boiling operation completion time predicted from the required boiling time t1 is earlier than the target end time (step S5). 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.

If the amount of heat required for boiling is appropriate for the rated heating capacity Q1 and the predicted boiling operation completion time is earlier than the target completion time, the controller 50 sets the value of the heating capacity of the heat pump unit 100 to Q1. , and the boiling operation is performed (step S6). 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 rated heating capacity Q1 and the predicted boiling operation completion time is not earlier than the target completion time, the control device 50 controls the heat pump unit 100 to heat. A required boiling time t2, which is the time required to generate the heat required for boiling with the capacity Q2, is calculated (step S7). Here, since the heating capacity Q2>the rated heating capacity Q1, the required boiling time t1>the required boiling 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 target end time (step S8).

If the required heat amount for boiling is appropriate for the heating capacity Q2 and the predicted boiling operation completion time is earlier than the target completion time, the control device 50 sets the value of the heating capacity of the heat pump unit 100 to Q2. After setting, the boiling operation is performed (step S9). 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 target completion time, the control device 50 sets the value of the heating capacity of the heat pump unit 100. is set to Q3 and the boiling operation is performed (step S10).

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 In addition, the control device 50 calculates the heat quantity required for boiling so that the heat quantity required for boiling increases as the late-night heat quantity used increases. Therefore, the control device 50 performs control so that the heating capacity when the amount of heat used at midnight is large is greater than the heating capacity when the amount of heat used at midnight is small in the boiling operation during the midnight hours. Therefore, even if the amount of heat used is large at midnight, the boiling operation can be reliably completed within the midnight time period.

According to the present embodiment, the heating capacity can be determined according to the amount of heat used at midnight predicted by control device 50 . Therefore, even the heat quantity of hot water that is expected to be used after the start of the boiling operation in the late-night time period can be reliably generated in the late-night time period. As a result, it is possible to prevent efficiency loss caused by changing the heating capacity during the boiling operation. In addition, even when a large amount of hot water is used in the late night hours, the boiling operation can be reliably completed within the late night hours. In addition, since the heating capacity in the late-night time zone is set to be greater than that in the daytime time zone, it is possible to enjoy the merits of a night-time heat storage type device stipulated by the electric power company.

In addition, in the present embodiment, the amount of heat released from the hot water storage tank 11 to the outside air is reduced by making the heating capacity of the boiling operation during the late-night hours greater than the heating capacity of the boiling operation during the daytime hours. be advantageous in doing so. The reason for this will be explained below. Assuming that the same amount of heat necessary for boiling is generated, the larger the heating capacity, the shorter the time required for the boiling operation, so the amount of heat radiated from the hot water storage tank 11 to the outside air during the boiling operation is reduced. In the present embodiment, since the heating capacity of the boiling operation in the late-night hours is set to a relatively large value, the amount of heat radiated from the hot water storage tank 11 to the outside air during the boiling operation becomes low, and when the boiling operation is completed. It becomes possible to increase the actual amount of heat stored in the hot water storage tank 11.

The control device 50 may perform processing for confirming whether or not the boiling operation can be completed by the target end time when hot water is used after starting the boiling operation in the late-night hours. The processing may be performed at a predetermined time after the start of the boiling operation, or may be performed each time a predetermined period of time elapses. When it is determined in the process that the boiling operation cannot be completed by the target end time, the control device 50 changes the heating capacity to a value larger than the current value and performs the boiling operation. As a result, the boiling operation can be completed more reliably by the target end time.

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 to be Q2 from the amount of heat necessary for boiling according to the flow chart 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 Q0 during the daytime boiling operation. Here, heating capacity Q0<rated heating capacity Q1.

The boiling operation in the daytime hours may include a plurality of operation modes with different heating capacity values. For example, in the boiling operation during the daytime hours, by setting the heating capacity to a different value according to the amount of heat to be generated, it is possible to avoid increasing the heating capacity more than necessary. As a result, it is possible to operate with a higher COP (coefficient of performance), so that it is possible to more reliably suppress an increase in power consumption during the heating operation during the daytime hours. Also, the heating capacity during the daytime may be changed according to the conditions of the water supply temperature, the outside air temperature, the learned hot water usage conditions, and the like. 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.

The controller 50 sets the target boiling temperature to be lower as the heating capacity of the heat pump unit 100 is smaller.

FIG. 5 is a diagram showing the relationship between the heating capacity of the heat pump unit 100 and the COP. As shown in FIG. 5, the COP tends to increase as the heating capacity decreases. In the present embodiment, during the daytime hours, the boiling operation is performed with a lower heating capacity than during the midnight hours, thereby enabling highly efficient operation with a high COP. On the other hand, the risk of running out of hot water when a large amount of hot water is used can be suppressed by performing the boiling operation with a higher heating capacity in the late-night hours than in the daytime hours. For these reasons, according to the present embodiment, it is possible to provide a heat pump water heater that achieves both energy saving and user convenience.

In addition, when carbon dioxide is used as the refrigerant of the heat pump unit 100, it is operated in a supercritical state on the high pressure side. high efficiency. Moreover, even when the heating operation is performed with the heating capacity reduced, the refrigerant is similarly operated in the supercritical state, so hot water of high temperature can be efficiently generated.

FIG. 6 is a diagram showing temporal changes in the boiling temperature after the boiling operation is started in the late-night hours. Immediately after the boiling operation is started, it is necessary to raise the temperature of the compressor 1 itself and the water-refrigerant heat exchanger 2 itself. Therefore, it takes a certain amount of time for the actual boiling temperature to reach the target boiling temperature. During this time, while the heat is released from both the compressor 1 and the water-refrigerant heat exchanger 2 as the temperature rises, the boiling temperature temporarily goes through a medium temperature (for example, about 20 to 50 ° C.), reach the target boiling temperature.

In general, when the heating capacity of the heat pump unit 100 is reduced, the COP is improved as described above, but the time required for the boiling temperature to reach the target boiling temperature is significantly lengthened. This is because the amount of heat radiation from components such as the compressor 1 and the water-refrigerant heat exchanger 2 depends on the temperature of the components and does not depend on the magnitude of the heating capacity of the heat pump unit 100, so the heating capacity is small. This is because the relative ratio of the amount of heat radiation to the heating capacity becomes large.

As shown in FIG. 6, the control device 50 of the present embodiment controls the rotation speed of the compressor 1 at the start of the boiling operation in the late-night time zone so that the boiling temperature reaches the target boiling temperature during the boiling operation. The rotation speed of the compressor 1 is controlled so as to be higher than the rotation speed of the compressor 1 after reaching the steady state. In the example shown in FIG. 6, the operating frequency of the compressor 1 at the start of the boiling operation is f1, and the operating frequency of the compressor 1 after the boiling temperature reaches the target boiling temperature is f2. Here, f1>f2.

By doing so, the following effects can be obtained. The temperature of components such as the compressor 1 and the water-refrigerant heat exchanger 2 can be raised in a short time, and the boiling temperature can reach the target boiling temperature in a short time after the start of the boiling operation. Therefore, it is possible to suppress the amount of medium-temperature water generated after the boiling operation is started. Since the temperature of the hot water in the hot water storage tank 11 can be suppressed from being lowered by the generated intermediate hot water, the time required for reheating the hot water in the bathtub becomes longer, and hot water runs out on days when the amount of hot water used is large. You can control what you do. Even when the heating capacity is relatively low, the increase in the time required for the boiling temperature to reach the target boiling temperature after the start of the boiling operation can be suppressed, so that the effect of improving the COP by lowering the heating capacity is obtained. be advantageous in some cases. As a result, it is possible to achieve both user convenience and energy saving. 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 As a result, the heat pump water heater of the present embodiment is treated as a nighttime heat storage type device, so that incentives for the nighttime heat storage type device (energization control discount, etc.) determined by each electric power company can be enjoyed.

If the value of the heating capacity of the boiling operation in the late-night time zone differs, the generated medium-temperature hot water affects the hot water already in the hot water storage tank 11 differently. FIG. 7 is a diagram showing an example of changes in temperature distribution in the hot water storage tank 11 before the start of the boiling operation and after the completion of the boiling operation in the middle of the night. In the following description, the amount of remaining hot water in the hot water storage tank 11 before the start of the boiling operation in the late-night hours is referred to as "pre-start remaining hot water amount". In FIG. 7, the case where the remaining hot water amount before the start is large and the heating capacity is Q1, the case where the remaining hot water amount before the start is medium and the heating capacity is Q2, and the case where the remaining hot water amount before the start is small and the heating capacity is Q3. and

As shown in FIG. 7, when the amount of remaining hot water before starting is medium or small, the amount of heat required for boiling is relatively large, so the boiling operation is performed with relatively high heating capacity of Q2 or Q3. As a result, the amount of intermediate hot water generated after the start of the boiling operation and supplied into the hot water storage tank 11 is relatively small.

On the other hand, when the amount of remaining hot water before starting is large, the amount of heat necessary for boiling is small, so the boiling operation is performed with a relatively low heating capacity Q1. As a result, the amount of intermediate hot water generated after the start of the boiling operation and supplied to the hot water storage tank 11 tends to increase.

On the other hand, in the present embodiment, the rotation speed of the compressor 1 at the start of the boiling operation in the late-night time zone is set to the compression speed after the boiling temperature reaches the target boiling temperature in the boiling operation. It is controlled to be higher than the rotation speed of the machine 1. As a result, even when the boiling operation is performed with the relatively low heating capacity Q1, the amount of medium-temperature water to be generated can be suppressed.

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. FIG. 8 is a diagram showing the remote control 51 when the value of the heating capacity during the boiling operation is displayed on the display section 51a. In the example shown in FIG. 8, "heating capacity: XX kW" is displayed on the display section 51a. Instead of displaying the value of the heating capacity itself on the display section 51a as in this example, a figure or the like indicating whether the heating capacity is large or small may be displayed on the display section 51a.

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.

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; and
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;
hot water supply heat amount calculation means for calculating the heat amount used for hot water supply;
with
The boiling operation in the midnight time zone includes a plurality of operation modes with different heating capacity values,
The control means calculates a late-night heat usage amount, which is a predicted value of the heat amount to be used in the late-night time zone, based on the value calculated by the hot water supply heat amount calculation means,
During the boiling operation in the late-night time zone, the control means subtracts the residual heat amount of the hot-water storage tank from the target heat storage amount required to be stored in the hot-water storage tank by the end of the late-night time zone. The amount of heat required for boiling is calculated by adding the amount of heat used at midnight to the value obtained, and the heating capacity when the amount of heat required for boiling is larger than the heating capacity when the amount of heat required for boiling is small controlled to grow,
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. The control means increases the heating capacity to a value exceeding the rated heating capacity when the required heat for boiling cannot be generated within the midnight time zone with the rated heating capacity. 3. The heat pump water heater according to claim 1 or 2 , which performs a boiling operation. 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 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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