JPS647291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a hot water storage type electric water heater that uses late-night electricity, which detects the temperature of water supplied to a hot water storage tank and calculates the required energization time to apply electricity to a heating element. The purpose is to reduce the amount of remaining hot water and heat loss after boiling by starting energization to the heating element in the middle of the late-night power supply time so that the required power supply time can be obtained at the same time as the end of the late-night power supply time. It is said that

FIG. 1 is a block diagram of a general hot water storage type electric water heater, and FIG. 2 is a main electrical circuit diagram of a conventional hot water storage type electric water heater.

In the figure, 1 is a hot water storage tank, 2 is a heating element, and 3
is an automatic temperature controller, 4 is a power supply, and 5 is a time switch for late-night power, which is generally turned on around 23:00.
8 hours from 7:00 to 7:00 the next morning.

Next, the operation of the conventional example having the above configuration will be explained. When the midnight power supply start time arrives, the contact of the time switch 5 is closed and the supply of electricity to the heating element 2 is started. And the water temperature in hot water storage tank 1 is 85℃.
When this happens, the contacts of the automatic temperature regulator 3 are opened and the power supply to the heating element 2 is stopped. Thereafter, the temperature of the water is maintained at 85°C by opening and closing the automatic temperature controller 3, and in this way, the entire amount of stored hot water is boiled to 85°C every morning.

In this way, in order to increase hot water storage efficiency, hot water storage type water heaters are designed to set the boiling temperature as high as possible and stop heating when the set temperature is reached. However, users do not use hot water as it is, but mix it with water and use it as a mixed hot water at around 40 to 45 degrees Celsius. The formula for determining the amount of mixed hot water obtained is as follows.

Now, the hot water storage tank capacity is Vt (), the boiling temperature in the hot water storage tank is T ₀ (℃), the temperature of the mixed hot water to be obtained is t (℃), and the temperature of the water to be mixed (water supply temperature) is t ₀ (°C), the amount of mixed hot water V() can be expressed as V=Vt×T ₀ −t ₀ /t−t ₀ ().

In this formula, the water supply temperature varies greatly depending on the season. In Tokyo, the temperature starts from around 5℃ in winter, and in summer
The temperature reaches around 27℃. For this reason, the amount of hot water that can be obtained as mixed hot water at an appropriate temperature is small in the winter and large in the summer. In other words, the boiling temperature T ₀
Assuming that 85℃, when the supply water temperature t ₀ is 5℃,
The amount of mixed hot water V obtained at 27℃ reaches 1.6 times.

On the other hand, the amount of hot water used is almost constant throughout the year, or in fact, the actual amount used is generally lower in the summer because hot water is used at a lower temperature, and the amount of hot water remaining in the summer is larger than in the winter. .

Therefore, if the water supply temperature is high or there is residual hot water, the hot water will boil quickly and the hot water will be left unused for a long time.

Leaving hot water at an unnecessarily high temperature unused for a long time like this has the disadvantage of increasing heat loss due to natural heat radiation from the hot water storage tank 1 and heat radiation from hot water stagnant in the pipes. It was hot.

The present invention aims to solve these drawbacks by detecting the temperature of the water supplied to the hot water storage tank, calculating the required energization time to the heating element so that a constant amount of mixed hot water is always obtained, and also calculating the required energization time. By starting energizing the heating element in the middle of the late-night power supply period so that the time can be used up by the time when the late-night power supply ends, the amount of remaining hot water is reduced and heat loss after boiling is eliminated as much as possible. be.

Hereinafter, one embodiment of the invention will be described based on the overall configuration diagram in FIG. 3 and the control flowchart in FIG. 4. In FIG. 3, reference numeral 6 denotes a temperature sensor such as a thermistor for continuously detecting the temperature of water supplied into the hot water storage tank 1, and is provided at the bottom of the hot water storage tank 1.

7 is a calorific value calculation means for calculating the calorific value to be stored as hot water in the hot water storage tank 1 from the rated supply amount of mixed hot water determined according to the water supply temperature detected by the temperature sensor 6 and the volume in the hot water storage tank 1; be. Reference numeral 8 denotes an energization time calculation means for calculating the required energization time H to the heating element 2 from the thermal calories calculated by the heat amount calculation means 7, and 9 is an energization time calculation means 8 that calculates the required energization time H for the heating element 2 from the thermal calories calculated by the heat amount calculation means 7. This is an energization start control means for starting energization of the heating element 2 in the middle of the late-night power energization time period so that the determined predetermined energization time H can be obtained. On the other hand, 10 is a boiling water temperature calculation means for calculating the temperature of hot water to be boiled from the thermal calories calculated by the heat amount calculation means 7, the volume in the hot water storage tank, and the water supply temperature, and 11 is a hot water storage tank. This is an energization stop control means for stopping energization to the heating element 2 when the temperature of the hot water in the boiling water reaches a predetermined temperature determined by the boiling water temperature calculation means 10.

Next, a specific example of the operation of the above configuration will be explained using formulas and the control flowchart shown in FIG. At midnight, the time switch turns on at 23:00.
power is supplied to the electric water heater (step
20). Control is started upon receiving this power ON signal (step 21).

Now, when boiling is performed so as to constantly supply mixed hot water with a rated supply amount of V liters (hot water temperature T°C) determined according to the volume inside the hot water storage tank 1, first, in step 25, a The temperature sensor 6 detects the temperature of the lower part of the hot water storage tank 1, that is, the temperature of the water supply. 11pm is the time when most of the daily hot water has been used, and the hot water tank 1
Since the lower part contains water supplied from a water source, it is possible to measure the temperature of the supply water here. Now, let us say that the water supply temperature detected by this temperature sensor 6 is t ₀ °C.

Next, in step 26, the calorific value calculation means 7 calculates the calorific value K ₁ (kcal) that should be stored as hot water by the end of the midnight power supply time.

The formula can be expressed as below.

K ₁ = (T - t ₀ ) x V (kcal) In the next step 27, the energization time calculation means 8 calculates H=K ₁ based on the heat amount K ₁ (kcal) calculated by the heat amount calculation means 7. /860×W (hr) to calculate the required time H (hr) for energizing the heating element 2, which is necessary to obtain the amount of heat that should be stored in the hot water storage tank 1 (1KWH=
860 kcal). Here, W represents the rated power consumption (KW) of the heating element 2.

Furthermore, in step 28, the required energization time H calculated in step 27 is determined at the end of the midnight power supply time.
It is used to judge the passage of time so that (hr) can be obtained.
When the time (8-H) has elapsed since the time switch was turned ON, the process proceeds to step 29, and the energization start control means 9 is activated.
energization to the heating element 2 is started.

On the other hand, in step 30, the boiling water temperature calculation means 10 calculates T ₀ =K ₁ /V ₂ +t ₀ (°C) based on the heat amount K ₁ calculated by the heat amount calculation means 7 (step 26), Calculate the temperature T ₀ (°C) of the water that should be boiled. Here, Vt represents the volume (liter) inside the hot water storage tank 1. Next, the detected value of the temperature sensor 6 is T ₀ °C
It is determined in step 31 whether the water temperature has reached
When the temperature reaches T ₀ °C, the process proceeds to step 32, where the current supply to the heating element 2 is stopped by the action of the current supply stop control means 11. The temperature sensor for detecting this hot water temperature is the temperature sensor 6 installed at the bottom of the hot water tank 1.
It may be provided separately.

In this kind of control, if there is no remaining hot water from the previous day, the time when the predetermined boiling water temperature T ₀ (°C) obtained by the boiling water temperature calculation means 10 is reached and the end of the late-night electricity supply, that is, the time switch is set. The OFF times of 5 will match.

However, under actual conditions of use, some residual hot water occurs every day (if there is no residual hot water, it means that the hot water ran out the previous day), so the predetermined boiling water temperature T ₀ (°C) is reached and heat is generated. The time your body turns off will be earlier by the amount of heat left in the water. Therefore, after the heating element 2 is turned off as shown in step 33, the time switch is turned off, and the series of controls ends (step 34).

As described above, the present invention includes a temperature detection means for detecting the temperature of water supplied into a hot water storage tank and the boiling temperature of hot water in the hot water storage tank, and a temperature detection means that detects the temperature of water supplied to a hot water storage tank and the boiling temperature of hot water in the hot water storage tank, and a A calorific value calculating means for calculating the thermal calories of the hot water to be stored from the rated supply amount of the mixed hot water to be determined, an energizing time calculating means for calculating the required energizing time to the heating element from the calculated thermal calorie, and this energizing time calculating means. an energization start control means for starting energization of the heating element in the middle of the late-night power energization time period so that the required energization time obtained by the means is obtained at the end time of the late-night power energization time; and a previously calculated thermal calorie. , a boiling water temperature calculation means for calculating the boiling water temperature from the volume in the hot water storage tank and the water supply temperature, and energizing the heating element when the boiling water temperature determined by the boiling water temperature calculation means is reached. It detects the temperature of the water supply and calculates the necessary heat calories so that a constant mixed hot water is obtained, and thereby calculates the required time of energization to the heating element to reduce late-night electricity. Since the structure is such that electricity is applied during the latter half of the electricity-on time period, the amount of remaining hot water is reduced, and the heat dissipation loss after boiling is reduced, resulting in lower maintenance costs.

In addition, since the device according to the present invention is mainly energized during the latter half of the late-night power supply period, if it is used in combination with conventional late-night power usage equipment whose load is concentrated in the first half, the power load during the first half of the power supply period will be reduced. It also has the effect of easing the peak and improving power transmission efficiency.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a typical hot water storage type electric water heater.
Fig. 2 is a main electrical circuit diagram of a conventional hot water storage type electric water heater, and Fig. 3 is an overall configuration diagram according to the present invention.
FIG. 4 also shows the control flowchart. 1 is a hot water storage tank, 2 is a heating element, 6 is a temperature sensor (temperature detection means), 7 is a calorific value calculation means, 8 is an energization time calculation means, 9 is an energization start control means, 10 is a boiling water temperature calculation means, 11 is the energization stop control means.

Claims (1)

[Claims] 1. Temperature detection means for detecting the temperature of water supplied to the hot water storage tank and the boiling temperature; Calorie calculation means for calculating the thermal calories of the amount of hot water that should be poured;
energization time calculation means for calculating the required energization time to the heating element from the thermal calories calculated by the heat amount calculation means;
energization start control means for starting energization of the heating element from the middle of the late-night power energization time period so that the required energization time calculated by the energization time calculation means is obtained at the end time of the late-night power energization time; a boiling water temperature calculating means for calculating the boiling water temperature from the thermal calories calculated by the means, the volume in the hot water storage tank, and the water supply temperature; and the boiling water temperature detected by the temperature detecting means is calculated by the hot water temperature calculating means. A control device for a hot water storage type electric water heater, comprising an energization stop control means for stopping energization to a heating element when the boiling temperature reaches a certain temperature.