JPH0212337B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boiling heat amount control method for a late-night electric water heater.

FIG. 1 is a block diagram of a conventional late-night power water heater. In the figure, 1 is a hot water storage tank, 2 is an electric heater, and 3 is a thermometer that detects the temperature of hot water. By the way, the late-night electric water heater energizes the electric heater 2 during the late-night electric power period until the temperature of the hot water in the hot water storage tank 1 reaches 85°C. In addition, Thermo 3 has a temperature of
When 85°C is detected, the electric heater 2 is mechanically shut off. Note that hot water is supplied from direction A, and water is supplied from direction A.

According to such a conventional operation control method, the amount of heat stored in the hot water storage tank 1 is expressed by the following equation.

Q=V×(85−ΘL) [Kcal] Where, V is the hot water storage tank capacity [], and ΘL is the water supply temperature [°C].

In this case, the amount of heat storage Q is determined not from the hot water supply load required by each household, but from the temperature of the water supply. On the other hand, as shown in Figure 2, the efficiency of a late-night electric water heater decreases when the hot water extraction rate is low. Efficiency here refers to the ratio of the amount of heat used to heat water to the electrical input (heat amount for boiling), and hot water extraction rate refers to the ratio of the amount of heat used to heat water used to the amount of heat used for boiling. Therefore, conventional late-night electric water heaters tend to boil water more than necessary, resulting in very poor efficiency. In other words, with conventional late-night electric water heaters, the hot water in the water heater tank is boiled to 85℃ regardless of the hot water supply load in each household (the stored hot water can be heated to an appropriate temperature by adding water during normal use). (The temperature is adjusted to a certain temperature), and the amount of heat stored in the tank is large.In households where hot water is stored in the tank, a large amount of boiled water remains in the tank, resulting in a large amount of wasted water.

An object of the present invention is to obtain a boiling heat amount control method for a late-night electric water heater that determines a hot water supply load suitable for each household using a learning function and performs highly efficient operation to use up as much hot water as possible.

In order to achieve the above object, the present invention measures and detects the residual water heat amount and boiling heat amount for each day based on several days of operation results in a late-night power water heater equipped with a built-in electric heater that uses late-night power. The total amount of heat consumed each day is calculated by subtracting the amount of heat from the remaining hot water from the amount of heat raised, and the average water supply water temperature for each day is measured and detected, and the relational expression between the total amount of heat consumed and the water supply water temperature is calculated by the least squares method. By substituting the water supply temperature at the start time of late-night electricity supply on that day into the above relational expression, the total amount of heat consumed on that day is predicted, and the amount of heat equivalent to the predicted total amount of heat consumed on that day is calculated by calculating the amount of heat equivalent to the predicted total amount of heat consumed on that day. The present invention provides a method for controlling the amount of boiling heat in a late-night electric water heater, which is characterized by storing heat in the water heater.
The present invention will be explained below using the drawings.

FIG. 3 is a configuration diagram showing an embodiment of the present invention.
In the figure, 1 is a hot water storage tank, 2 is an electric heater,
3 is a thermostat attached to the side wall of the water supply pipe 4 for detecting the temperature of the water supply. Further, 5 is a hot water supply pipe, and 6 is a rod-shaped semiconductor thermometer attached to the side wall of the hot water storage tank 1 to detect the average temperature of hot water in the hot water storage tank 1. 7 inputs the signals of the thermostat 3 and the thermostat 6, and also has arithmetic ability to control the electric heater 2.
This is a calculation device that controls the opening and closing of energization. By the way, the thermometer 6 has a resistance-temperature characteristic as shown in Figure 4, so the hot water storage tank 1 can be determined from the resistance value.
You can know the average temperature of the water inside.

In the late-night power water heater of the present invention, the procedure for calculating the total amount of heat used on the previous day is as follows.
The current time is the start time of the late-night power period.
Assuming that it is 23:00, the residual hot water heat quantity QR at that time is approximately expressed by the following formula.

QR=V×(ΘW-ΘL) [Kcal] Where, V is the hot water storage tank capacity [ ], ΘW is the average hot water temperature at the current time measured by Thermo 6 [℃], and ΘL is the water supply temperature at 23:00 the previous day measured by Thermo 3 [℃] ].

Next, if the amount of boiling heat from the previous day is QB, QB is expressed by the following formula.

QB = V × (ΘH - ΘL ^* ) - QR ^* [Kcal] However, ΘH is the average water temperature determined by thermometer 6 at the time of completion of boiling the previous day [℃], and ΘL ^* is the temperature determined by the thermometer at the time of completion of boiling the previous day or at 11:00 p.m. the previous day. Water supply temperature according to 3 [℃],
QR ^* is the residual heat value of hot water [Kcal] at 11:00 pm the previous day.

Therefore, the total amount of heat including the amount of heat radiation used on the previous day can be calculated as QC = QB - QR [Kcal]. QC can also be said to be the amount of heat required for boiling per day. Here, we will rearrange the symbols to make the formula easier to understand.

Let the water supply temperature at 23:00 on a certain day i be x _i [°C], and the required amount of boiling heat for that day be y _i [Kcal]. The relationship between x and y for n days is the straight line 1 shown in Figure 5.
It can be approximated by the following formula. That is, it is approximately expressed as y=A·x+B.

If we process this using the least squares method, we get the following.

A=nΣx _i y _i −Σx _i Σy _i /nΣx _i ² −(Σx _i ) ² B=Σx _i Σx _i y _i −Σx _i ² Σy _i /(Σx _i ) ² −nΣx _i ^2Therefore , on the day 23 If the water supply temperature at the time is Θ, the required amount of boiling heat is determined as y=A·Θ+B. In other words, in the present invention, the amount of boiling heat is controlled each day according to the required amount of boiling heat calculated from a relational expression determined based on operational results over several days, so when the hot water supply load is small, the amount of stored heat is is set low (if the amount of hot water to be boiled is constant, the temperature of the hot water will be low), and a large amount of boiled water will not remain unused.

In general, the hot water supply load is greatly influenced by whether or not a person takes a bath, so it is preferable that the boiling heat amount control method of the present invention is carried out on days when bathing and days when there is no bathing. That is, n days of data are processed on days when the user takes a bath, and if the user takes a bath on that day, that data is used, and if the user does not take a bath, the result of processing the n days' worth of data is used only on days when the user does not take a bath. In this case, a switch for selecting whether to take a bath or not is required as an input to the arithmetic unit 7.

As is clear from the above description, according to the present invention, it is possible to reliably use up all the hot water in late-night electric water heaters every day for an unspecified number of households with different family structures and lifestyles. It is possible to achieve remarkable effects such as enabling highly efficient operation of the equipment, and the effects of implementation are significant.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional late-night electric water heater, Figure 2
Fig. 3 is a diagram showing the relationship between hot water extraction rate and efficiency of a late-night electric water heater, Fig. 3 is a configuration diagram showing an embodiment of the present invention, Fig. 4 is a diagram showing the resistance-temperature characteristics of the thermostat, and Fig. 5 is a diagram showing the relationship between hot water extraction rate and efficiency of a late-night electric water heater.
The figure is a line diagram showing the relationship between the water supply temperature and the required amount of boiling heat per day using a linear approximation. 1... Hot water storage tank, 2... Electric heater, 3, 6... Thermo, 7... Arithmetic device.

Claims (1)

[Claims] 1. In a method for controlling the amount of boiling heat of a late-night power water heater equipped with a built-in electric heater that utilizes late-night power, the remaining water heat and boiling heat for each day are measured and detected from several days of operation results. Then, by subtracting the remaining heat amount from the boiling heat amount, the total heat consumption for each day is calculated, and the average water supply water temperature for each day is measured and detected, and a relational expression between the total heat consumption and the water supply water temperature is calculated. is calculated by the least squares method, and by substituting the water supply temperature at the start time of late-night power supply on that day into the above relational expression, the total amount of heat consumed on that day is predicted, and the amount of heat equivalent to the predicted total amount of heat consumed on that day is calculated. A method for controlling the amount of boiling heat in a late-night electric water heater, characterized in that heat is stored in the late-night electric water heater. 2. Claim 1, characterized in that the total amount of heat consumed is calculated separately on days when bathing and days when bathing is not performed, and the amount of boiling heat is controlled separately for days when bathing and days when bathing is not performed. The boiling heat amount control method of the late-night electric water heater described.