JP7544249B2 - Storage water heater - Google Patents

Description

This disclosure relates to a storage type water heater.

In a given power supply area where electricity is supplied by a power company, the amount of power consumed varies from time to time. If the amount of power consumed in a power supply area increases and exceeds the amount of power supplied to that power supply area, there is a risk of a large-scale blackout. Therefore, it is desirable to achieve a balance between the amount of power supplied and the amount of power consumed.

In this regard, for example, Japanese Patent Application Laid-Open Publication No. 2016-125733 describes a hot water supply control system that determines the number of heat pump units that perform heating operation among multiple heat pump water heaters based on the amount of power supplied to a specified power supply area and the predicted power consumption of electrical equipment. This hot water supply control system aims to balance the amount of power supply and the amount of power consumption by limiting the number of heat pump units that perform heating operation.

JP 2016-125733 A

Even when the target heating capacity of a heat pump water heater is the same, the COP (coefficient of performance) changes depending on the outside air temperature and the temperature of water entering the heat pump. For this reason, the actual power consumption during heating does not necessarily match the predicted power consumption. If the actual power consumption is greater than the predicted power consumption, there is a risk that the power consumption will exceed the target power consumption in a control system that determines the number of heat pump units in operation based on the predicted power consumption.

In order to solve the problems described above, the present disclosure aims to provide an improved storage type water heater that makes it easier to adjust power consumption to the allowable peak power value even when the COP of the storage type water heater changes.

The hot water storage type hot water heater according to the present disclosure includes a heating means having a heat pump cycle driven by electricity to heat water and capable of changing the heating capacity, a hot water storage tank, and a control unit that controls a boiling operation in which hot water heated by the heating means is stored in the hot water storage tank. The control unit is configured to execute the boiling operation by adjusting the heating capacity of the heating means so that the power consumption during the boiling operation is equal to or less than a power consumption indication value that is set as an upper limit of power available for the boiling operation, and is configured to calculate a required power consumption, which is the power consumed by the heating means to store hot water in the hot water storage tank by the time the boiling operation is completed, to obtain a target heat storage amount to be secured in the hot water storage tank.
The storage type water heater of the present disclosure is configured to be able to communicate with an energy management device that controls and monitors the power consumption of the storage type water heater and other electrical equipment installed in the management area and transmits a power consumption instruction value to a control unit, and the control unit may be configured to transmit the required power consumption to the energy management device when the power consumption instruction value is smaller than the required power consumption.
Alternatively, the storage type water heater of the present disclosure may further include an input means for accepting operational input of commands from a user regarding the operating behavior and setting values of the storage type water heater, and may be configured such that when the power consumption instruction value, which is set as the upper limit of the power available for boiling operation, is smaller than the required power consumption, the user can select whether to set the heating capacity based on the power consumption instruction value or the required power consumption by operational input from the input means, and when the control unit selects to set the heating capacity based on the power consumption instruction value and the power consumption instruction value is smaller than the required power consumption, the control unit may perform boiling operation by adjusting the heating capacity of the heating means within a range such that the power consumption in boiling operation is equal to or less than the power consumption instruction value.

By adjusting the heating capacity during boiling operation so that it is below the power consumption indication value, power consumption can be easily adjusted so as not to exceed the peak power allowable value.

1 is a schematic diagram showing the configuration of a storage type water heater and its peripheral equipment according to a first embodiment of the present disclosure. FIG. 1 is a flowchart for explaining the control operation of the boiling operation of the storage type water heater according to the first embodiment of the present disclosure. A figure for explaining the control of the adjustment of the power consumption instruction value performed between the storage type water heater and the HEMS in embodiment 1 of the present disclosure. 11 is a flowchart showing the operation of the storage type hot water heater according to the first embodiment of the present disclosure when the minimum required power consumption is greater than the power consumption indication value.

Hereinafter, the embodiment will be described with reference to the drawings. The same reference numerals are used to designate common or corresponding elements in each drawing, and duplicated descriptions are simplified or omitted. In this embodiment, the calorific value of hot water is calculated as the difference in the calorific value of water at the same temperature as the water supplied from the water source. In this embodiment, the calorific value of hot water is described in principle in units of the amount of hot water [L] when converted into the calorific value of hot water at a predetermined reference hot water supply temperature. An example of the value of the reference hot water supply temperature is 40°C. In this disclosure, when simply referring to "water" or "hot water", liquid water at any temperature can be included, from low-temperature water to high-temperature water.

Embodiment 1.
Fig. 1 is a schematic diagram showing an overall configuration of a system including a storage type water heater and its peripheral devices according to the first embodiment of the present disclosure. As shown in Fig. 1, a storage type water heater 35 is installed in each of the general houses 1a and 1b. However, the installation location of the storage type water heater 35 is not limited to a general house. The storage type water heater 35 may be, for example, a household type, or a commercial type used in a facility or the like.

1, the hot water storage type water heater 35 is a hot water storage type heat pump water heater including a hot water storage tank unit 33 and a heat pump unit (hereinafter "HP" unit) 7. The HP unit 7 and the hot water storage tank unit 33 are connected via pipes 16 and 17 through which water flows, and electrical wiring (not shown).

The HP unit 7 is driven by electricity and functions as a heating means for heating low-temperature water guided from the hot water storage tank 8 provided in the hot water storage tank unit 33. The HP unit has devices such as a compressor, a water-refrigerant heat exchanger, an expansion valve, and an air heat exchanger. These devices are connected in a ring shape by piping or the like to form a refrigerant circuit that circulates the refrigerant using the compressor. The refrigerant circuit corresponds to a heat pump cycle that heats water. The water-refrigerant heat exchanger heats the water that flows in from the inlet with the refrigerant and discharges the heated water from the outlet. The air heat exchanger exchanges heat between the air and the refrigerant.

The value of the heating capacity of the refrigerant circuit of the HP unit 7 can be changed. In the following description, the heating capacity of the refrigerant circuit of the HP unit 7 may be simply referred to as "heating capacity". The heating capacity corresponds to the amount of heat that the HP unit 7 provides to water per hour. The unit of heating capacity is, for example, kW (kilowatts).

The compressor of the HP unit 7 is driven by a drive device (not shown) equipped with, for example, an inverter-controlled DC brushless motor. In this case, the drive device can adjust the compressor rotation speed to change the pressure and temperature of the refrigerant discharged from the compressor, or to change the heating capacity. However, the hot water storage type water heater 35 is not limited to using such a drive device, and may be configured, for example, to have multiple compressors installed in the HP unit 7, and to change the pressure and temperature of the discharged refrigerant, or the heating capacity, by switching the number of compressors in operation.

The hot water storage tank unit 33 contains various components and piping. The hot water storage tank 8 is for storing hot water. A number of hot water temperature sensors (not shown) are attached at different heights to the surface of the hot water storage tank 8. By detecting the temperature distribution of the hot water in the hot water storage tank 8 with these hot water temperature sensors, the amount of remaining hot water and the amount of stored heat in the hot water storage tank 8 can be ascertained.

The control unit 36 and the remote control 44 are connected to each other via wire or wirelessly so that they can communicate in both directions. The control unit 36 and the remote control 44 may also be able to communicate via a network. The remote control 44 is an example of a user interface. The remote control 44 has a display unit that displays information and an operation unit that can be operated by the user. The remote control 44 may be equipped with a touch screen that has the functions of both the display unit and the operation unit.

The operation unit of the remote control 44 functions as an input means for accepting operation input of commands related to the operation and setting values of the storage type hot water heater 35. A person such as a user can remotely operate the storage type hot water heater and perform various settings by operating the operation unit. The display unit functions as a notification means for notifying a person such as a user of information. The remote control 44 in this embodiment is equipped with a display unit as a notification means, but as a modified example, it may be equipped with other notification means such as a voice guidance device. The remote control 44 may be installed on a wall of, for example, a kitchen, living room, bathroom, etc. Alternatively, a mobile information terminal such as a smartphone may be configured to have a function as a user interface like the remote control 44. A configuration in which multiple remote controls 44 can communicate with the control unit 36 may be used.

The hot water storage tank unit 33 has a built-in control unit 36. The hot water storage type water heater 35 may have a control unit connected to each of the hot water storage tank unit 33 and the HP unit 7 so as to be able to communicate in both directions, for example. In this case, these control units work together to control the operation of the hot water storage type water heater. The control unit 36 includes a microcomputer having a memory and a processor, etc.

The control unit 36 receives inputs of the outputs of various sensors equipped in the hot water storage type hot water heater 35 and information on the user's operation of the remote control 44. The control unit 36 is also electrically connected to various valves, pumps, etc. equipped in the hot water storage tank unit 33 and the HP unit 7. Based on input information from the various sensors and the remote control 44, the control unit 36 controls the operation of the HP unit 7 and the hot water storage tank unit 33 by controlling the operating state of the pumps built into the HP unit 7 and the hot water storage tank unit 33 and the flow direction or switching position of the valves, etc. For example, the control unit 36 executes a boiling operation, etc., as described below, and controls the boiling temperature during the boiling operation and the heating capacity of the HP unit 7.

The control unit 36 is communicatively connected to an external device, the energy management system 50. The energy management system 50 is a system called a HEMS (Home Energy Management System), and is connected to a plurality of electrical devices used in each of the houses 1a and 1b to be managed, and controls and manages these. In the following description, the energy management system 50 will be referred to as "HEMS 50". The electrical devices managed by the HEMS 50 are communicatively connected to the HEMS 50. These electrical devices may include, in addition to a storage type water heater, home appliances such as an induction cooking heater, a washing machine, a television, and a refrigerator, air conditioners, lighting equipment, a ventilation fan, a power storage facility, and the like.

The HEMS 50 can receive information from the power supplier, which is the main entity of the system power supply or power generation equipment, via the Internet, for example. In each of the multiple homes 1a, 1b, the HEMS 50 receives an instruction for the allowable peak power, which is the maximum allowable power usage, from the power supplier. The HEMS 50 calculates a power consumption instruction value for the storage type water heater 35 based on the allowable peak power. The power consumption instruction value is a target value within which the power consumption of the storage type water heater 35 should be kept. Upon receiving the power consumption instruction value from the HEMS 50, the control unit 36 adjusts the heating capacity of the HP unit 7 and operates it so that the power consumption during boiling operation is equal to or less than the power consumption instruction value.

The control unit 36 performs a boiling operation during the late night hours to boil the required amount of hot water and store it in the hot water storage tank 8. The "late night hours" are low-cost electricity hours when the unit price of electricity is cheaper than other times of the day. By securing the required amount of hot water during the late night hours when the unit price of electricity is cheaper, the electricity fee can be reduced. In the following explanation, the time periods other than the late night hours are referred to as "non-late night hours". The unit price of electricity is higher during the non-late night hours than during the late night hours. For example, if the time period from 1:00 a.m. to 6:00 a.m. corresponds to the late night hours, the time period from 6:00 a.m. to 1:00 a.m. the following day corresponds to the non-late night hours. The start time and end time of the late night hours and non-late night hours are not limited to this example, and may change depending on the contract with the power supplier, etc. In this disclosure, a "day" is defined as consisting of the late night hours and the non-late night hours before that. The control unit 36 stores information on the start time and end time of the late night hours and non-late night hours. The control unit 36 has a timer function and can determine whether the current time is in a late-night time zone or a non-late-night time zone. The control unit 36 may also obtain information on the start time and end time of the late-night time zone and the non-late-night time zone from the remote control 44 or the HEMS 50.

The control unit 36 constantly calculates the target heat storage amount, which is the amount of heat that needs to be stored in the hot water storage tank 8, as the required hot water storage amount. Specifically, for example, the control unit 36 calculates the amount of heat used for hot water supply based on the water supply temperature, hot water supply temperature, and hot water supply flow rate detected by various sensors installed in the hot water storage tank unit 33. The control unit 36 stores data on the amount of heat used for hot water supply calculated over a predetermined period of time in the past (for example, the past two weeks), and learns the amount of heat used for hot water supply by, for example, statistically processing the amount of heat used for hot water supply over the predetermined period of time in the past. The control unit 36 may be configured to learn the amount of heat used for hot water supply for each hour of the day. The required hot water storage amount is calculated based on the learned amount of heat used for hot water supply.

Figure 2 is a flow chart for explaining the control operation of the boiling operation. The operation of the boiling operation will be explained using Figure 2. The control operation of Figure 2 is repeatedly executed at a fixed control interval.

First, in step S10, a power consumption command value is obtained from the HEMS 50. Next, in S11, an estimated heating capacity is calculated. The estimated heating capacity is a heating capacity value that does not exceed the power consumption command value estimated from the energy consumption efficiency estimated by obtaining the outside air temperature and the inlet water temperature to the HP unit 7, or a combination of the obtained outside air temperature, inlet water temperature, and target hot water storage temperature, and the power consumption command value.

Next, the remaining hot water volume is obtained in S12, and the boiling start time is calculated in S13. First, the boiling time required to boil the difference between the required hot water volume and the remaining hot water volume using the estimated heating capacity is calculated. Then, the time that is one boiling time before the target time for completing boiling of the required hot water volume is calculated as the boiling start time.

For example, if the required amount of hot water storage at the target time of 7:00 a.m. is 500 L at 40°C, the remaining amount of hot water is 50 L at 40°C, and the estimated heating capacity is 4 kW, then the boiling time will be approximately 4 hours, so the boiling start time will be 3:00 a.m.

In step S14, it is determined whether the time to start boiling has arrived. If it is not the time to start boiling in step S14, the current process ends. On the other hand, if it is determined in step S14 that the time to start boiling has arrived, boiling operation is started with the calculated estimated heating capacity, and after the required amount of hot water is stored, boiling is terminated and the current process ends.

Furthermore, in the storage type hot water heater 35 of this embodiment, the control unit 36 always calculates the minimum required power consumption and transmits this to the HEMS, thereby controlling the adjustment of the power consumption between the control unit 36 and the HEMS 50. Figure 3 is a diagram for explaining the control of the adjustment of the power consumption instruction value performed between the control unit 36 and the HEMS 50. This control will be explained below with reference to Figure 3.

3, in step S21, the control unit 36 acquires the amount of heat used for hot water supply, and in step S22, calculates the minimum required heating capacity to avoid running out of hot water at the current time based on the amount of heat used for hot water supply. The minimum required heating capacity is calculated, for example, from the start time of the late-night period when electricity rates are lower and the required amount of hot water storage at the end time of the non-late-night period so that boiling can be completed during the late-night period. In addition, the time when the required amount of hot water storage needs to be secured is also taken into consideration. As an example, if the late-night period is five hours from 1:00 a.m. to 6:00 a.m., the required amount of hot water storage at 7:00 a.m. is 500 L converted to 40° C., and the remaining amount of hot water is 50 L converted to 40° C., the minimum required heating capacity is approximately 3 kW. However, the minimum required heating capacity may be calculated without considering the non-late-night period, for example, by setting the time when the required amount of hot water storage needs to be secured as the time when boiling is completed.

Next, in step S23, the minimum required power consumption is calculated for the calculated minimum required heating capacity from either the outside air temperature, the inlet water temperature to the HP unit 7, or the target hot water storage temperature, or a combination thereof. The calculated minimum required power consumption is transmitted to the HEMS 50 in step S24.

In step S30, the HEMS 50 receives the minimum required power consumption. In step S31, the HEMS 50 recalculates the power consumption instruction value for each electrical device managed by the HEMS 50 based on the minimum required power consumption, and re-determines the power consumption instruction value for the storage type water heater 35. In the following step S32, the HEMS 50 transmits the determined power consumption instruction value to the control unit 36 of the storage type water heater 35 and other electrical devices managed by the HEMS 50.

The control unit 36 receives the power consumption instruction value recalculated in step S25. Then, in step S26, the control unit 36 recalculates the boiling start time based on the power consumption instruction value, following the procedure in Fig. 2. In this way, the power consumption instruction value is readjusted based on the minimum required power consumption, thereby reducing the risk of running out of hot water.

Next, we will explain the processing when the power consumption instruction value is smaller than the minimum required power consumption. Figure 4 is a flowchart showing the operation when the power consumption instruction value is smaller than the minimum required power consumption.

As shown in FIG. 4, in step S41, it is determined whether the power consumption instruction value is lower than the minimum required power consumption. The power consumption instruction value is the most recent power consumption instruction value last received by the control unit 36. If it is determined in step S41 that the power consumption instruction value is equal to or greater than the minimum required power consumption, the current process ends. That is, by the process of FIG. 2, boiling is performed at the boiling start time with the estimated heating capacity.

On the other hand, if it is determined in step S41 that the power consumption indication value is lower than the minimum required power consumption, then in step S42 it is determined whether or not to prioritize suppression of peak power. The user can set in advance via the remote control 44 whether to prioritize suppression of peak power or to prioritize reducing the risk of running out of hot water as the process to be taken when the power consumption indication value is lower than the minimum required power consumption. Therefore, the determination process in step S42 is performed according to the currently set indication.

If it is determined in step S42 that peak power suppression is to be prioritized, in step S50, the heating capacity of the HP unit 7 during boiling operation is set to an estimated heating capacity, which is a heating capacity that does not exceed the power consumption indication value.

Next, in step S51, the remote control 44 displays a message indicating that the required amount of hot water may not be available, thereby informing the user of the risk of running out of hot water. The process then ends.

On the other hand, if it is determined in step S42 that suppression of peak power is not a priority, i.e., if reducing the risk of running out of hot water is a priority, the process proceeds to step S60. In step S60, the heating capacity of the HP unit 7 during boiling operation is set to the minimum required heating capacity.

Next, in step S61, the user is notified by a display on the remote control 44 that there is a possibility that the peak power of power consumption cannot be suppressed. Next, in step S62, excess heating capacity information is transmitted to the HEMS 50. The current processing of the control unit 36 then ends. Having received the excess information, the HEMS 50 adjusts the peak power of all electrical equipment as much as possible.

As described above, according to this embodiment, by performing boiling operation by adjusting the heating capacity so that the power consumption is equal to or less than the power consumption command value, it is possible to easily adjust the power consumption relative to the allowable peak power. In addition, by transmitting the minimum required power consumption to the HEMS 50 and adjusting the power consumption between the HEMS 50, it is possible to ensure a high degree of freedom in adjusting the power consumption relative to the allowable peak power.

In this embodiment, the case where the HEMS 50 has the function of instructing the power consumption command value has been described, but the control unit 36 may also be configured to have the function of acquiring the power consumption command value. For example, in the case of a power contract in which the basic fee varies depending on peak power, the power consumption command value may be set from the remote control 44 without using the HEMS 50. In this case, the control unit 36 receives the power consumption command value from the remote control 44, and operates by adjusting the heating capacity so that the power consumption during boiling operation is equal to or less than the power consumption command value, in the same manner as described in FIG. 2. This similarly makes it possible to suppress peak power.

1a, 1b House, 7 HP unit, 8 Hot water tank, 16 Piping, 17 Piping, 33 Hot water tank unit, 35 Hot water heater, 36 Control unit, 44 Remote control, 50 Energy management system (HEMS)

Claims (10)

A hot water storage type water heater configured to be able to communicate with an energy management device,
A heating means that is driven by electricity, has a heat pump cycle for heating water, and has a variable heating capacity;
A hot water tank and
A control unit that controls a boiling operation in which the hot water heated by the heating means is stored in the hot water storage tank;
Equipped with
The control unit is configured to adjust the heating capacity of the heating means to perform the boiling operation so that the power consumption during the boiling operation is equal to or less than a power consumption instruction value set as an upper limit value of power available for the boiling operation,
The energy management device is configured to control and monitor the power consumption of the storage type hot water heater and other electrical appliances installed in a management area, and to transmit the power consumption instruction value to the control unit;
The control unit further
Calculating a required power consumption, which is the power consumed by the heating means to store a target amount of heat storage in the hot water storage tank by a time when the water heating is completed;
If the power consumption instruction value is smaller than the required power consumption, the required power consumption is transmitted to the energy management device.
A storage type hot water heater characterized by being configured as follows. A heating means that is driven by electricity, has a heat pump cycle for heating water, and has a variable heating capacity;
A hot water tank and
A control unit that controls a boiling operation in which the hot water heated by the heating means is stored in the hot water storage tank;
An input means for receiving operation inputs of commands from a user regarding the operation and setting values of the storage type hot water heater;
Equipped with
When a power consumption command value set as an upper limit value of power available in the boiling operation is smaller than a required power consumption, the heating capacity is set based on either the power consumption command value or the required power consumption, and the heating capacity is configured to be selectable by an operation input from the input means;
The control unit is
Calculating the required power consumption, which is the power consumed by the heating means to store the target amount of heat storage to be secured in the hot water storage tank by the time the water heating is completed;
When it is selected to set the heating capacity according to the power consumption command value, if the power consumption command value is smaller than the required power consumption, the heating capacity of the heating means is adjusted within a range in which the power consumption in the boiling operation is equal to or less than the power consumption command value, thereby performing the boiling operation.
A storage type hot water heater characterized by being configured as follows. The hot water storage type water heater according to claim 1, characterized in that, when the power consumption command value is smaller than the required power consumption, the control unit executes the heating operation by exceeding the power consumption command value. Further comprising a notification means capable of notifying a user of information regarding the operation of the hot water storage type hot water heater,
The storage type water heater of claim 3, characterized in that when the power consumption instruction value is smaller than the required power consumption and the heating operation is performed exceeding the power consumption instruction value, the control unit notifies the user by the notification means that there is a possibility that peak power consumption cannot be suppressed. The hot water storage type water heater according to claim 1, characterized in that, when the power consumption indication value is smaller than the required power consumption, the control unit executes the heating operation in a range in which the power consumption in the heating operation is equal to or less than the power consumption indication value. Further comprising a notification means capable of notifying a user of information regarding the operation of the hot water storage type hot water heater,
The storage type water heater of claim 4 or 5, characterized in that when the power consumption instruction value is smaller than the required power consumption, and the heating operation is performed in a range where the power consumption in the heating operation is equal to or less than the power consumption instruction value, the control unit notifies the user by the notification means that there is a possibility that the target heat storage amount cannot be secured. Further comprising an input means for receiving an input of a command from a user regarding the operation and setting values of the storage type hot water heater,
When the power consumption command value is smaller than the required power consumption, the heating capacity is set based on either the power consumption command value or the required power consumption, and the heating capacity is set based on the power consumption command value or the required power consumption, which is selected by an operation input from the input means.
7. The storage type hot water heater according to claim 1, wherein the hot water supply is a water heater. The control unit is
Calculating an estimated value of the heating capacity of the heating means based on at least one of a target amount of heat storage to be secured in the hot water storage tank, the power consumption indication value, an outside air temperature, and an inlet water temperature to the heating means;
starting the boiling operation so as to ensure the target heat storage amount at a preset target time based on the target heat storage amount and the estimated value of the heating capacity;
8. The hot water storage type hot water heater according to claim 1, wherein the hot water storage type hot water heater is configured as follows. 9. The storage type hot water heater according to claim 1, wherein the boiling completion time is a time before a time when it becomes necessary to secure the target heat storage amount. A storage type water heater as described in any one of claims 1 to 8, characterized in that the time of completion of boiling is set to a time before the time when the target heat storage amount needs to be secured and within a range of low electricity rates, which is a time period when electricity rates are cheaper than other time periods.

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